Adherent cell function in murine T-lymphocyte antigen recognition. IV. Enhancement of murine T-cell antigen recognition by human leukocytic pyrogen

Stimulating the Antitumor Immune Response Using Immunocytokines: A Preclinical and Clinical Overview

Cytokines are immune modulators which can enhance the immune response and have been proven to be an effective class of immunotherapy. Nevertheless, the clinical use of cytokines in cancer treatment has faced several challenges associated with poor pharmacokinetic properties and the occurrence of adverse effects. Immunocytokines (ICKs) have emerged as a promising approach to overcome the pharmacological limitations observed with cytokines. ICKs are fusion proteins designed to deliver cytokines in the tumor microenvironment by taking advantage of the stability and specificity of immunoglobulin-based scaffolds. Several technological approaches have been developed. This review focuses on ICKs designed with the most impactful cytokines in the cancer field: IL-2, TNFα, IL-10, IL-12, IL-15, IL-21, IFNγ, GM-CSF, and IFNα. An overview of the pharmacological effects of the naked cytokines and ICKs tested for cancer therapy is detailed. A particular emphasis is given on the immunomodulatory effects of ICKs associated with their technological design. In conclusion, this review highlights active ways of development of ICKs. Their already promising results observed in clinical trials are likely to be improved with the advances in targeting technologies such as cytokine/linker engineering and the design of multispecific antibodies with tumor targeting and immunostimulatory functional properties.

Human genetic errors of immunity illuminate an adaptive arsenal model of rapid defenses

New discoveries in the field of human monogenic immune diseases highlight critical genes and pathways governing immune responses. Here, I describe how the ~500 currently defined human inborn errors of immunity help shape what I propose is an 'adaptive arsenal model of rapid defenses', emphasizing the set of immunological defenses poised for rapid responses in the natural environment. This arsenal blurs the lines between innate and adaptive immunity and is established through molecular relays between cell types, often traversing from sensors (pathogen detection) to intermediates to executioners (pathogen clearance) via soluble factors. Predictions and missing information based on the adaptive arsenal model are discussed, as are emergent and outstanding questions fundamental to advances in the field.

TLR5 ligand induces the gene expression of antimicrobial peptides and CXCL8 through IL-1β gene expression in cultured rumen epithelial cells

High grain feeding or weaning, which could compromise the rumen epithelium by increasing ruminal short-chain fatty acid (SCFA) concentrations with pH reduction, is associated with high levels of ruminal toll-like receptor 5 (TLR5). This study aimed to determine the role of TLR5 in the rumen epithelium. Immunohistochemistry revealed that TLR5 was localized in cells on the basal side (i.e., basal and spinous layers) rather than in the granular layer in the rumen epithelium, where tight junctions are most potent, in pre- and post-weaning calves (n = 9). Primary bovine rumen epithelial cells (BRECs) obtained from Holstein cows (n = 3) were cultured to investigate the factors that upregulate TLR5; however, SCFA, low pH (pH 5.6), BHBA, L-lactate, D-lactate, and LPS did not upregulate TLR5 gene expression in BREC. Primary BREC treated with flagellin (TLR5 ligand) had higher expression of interleukin-1β (IL-1β) (P < 0.05) than BREC treated with vehicle. In addition, BREC treated with IL-1β had higher expression of antimicrobial peptides and C-X-C motif chemokine ligand 8 than BREC treated with vehicle (P < 0.05). These results suggest that ruminal TLR5 may recognize epithelial disruption via flagellin and mediate the immune response via IL-1β during high-grain feeding or weaning.

What Is IL-1 for? The Functions of Interleukin-1 Across Evolution

Interleukin-1 is a cytokine with potent inflammatory and immune-amplifying effects, mainly produced by macrophages during defensive reactions. In mammals, IL-1 is a superfamily of eleven structurally similar proteins, all involved in inflammation or its control, which mainly act through binding to specific receptors on the plasma membrane of target cells. IL-1 receptors are also a family of ten structurally similar transmembrane proteins that assemble in heterocomplexes. In addition to their innate immune/inflammatory effects, the physiological role of IL-1 family cytokines seems to be linked to the development of adaptive immunity in vertebrates. We will discuss why IL-1 developed in vertebrates and what is its physiological role, as a basis for understanding when and how it can be involved in the initiation and establishment of pathologies.

Advances on the Role and Applications of Interleukin-1 in Tuberculosis

Interleukin-1 (IL-1) is a key player in the immune response to pathogens due to its role in promoting inflammation and recruiting immune cells to the site of infection. In tuberculosis (TB), tight regulation of IL-1 responses is critical to ensure host resistance to infection while preventing immune pathology. In the mouse model of Mycobacterium tuberculosis infection, both IL-1 absence and overproduction result in exacerbated disease and mortality. In humans, several polymorphisms in the IL1B gene have been associated with increased susceptibility to TB. Importantly, M. tuberculosis itself has evolved several strategies to manipulate and regulate host IL-1 responses for its own benefit. Given all this, IL-1 appears as a promising target for host-directed therapies in TB. However, for that to succeed, more detailed knowledge on the biology and mechanisms of action of IL-1 in vivo, together with a deep understanding of how host-M. tuberculosis interactions modulate IL-1, is required. Here, we discuss the most recent advances in the biology and therapeutic potential of IL-1 in TB as well as the outstanding questions that remain to be answered.

Damage-associated molecular patterns in trauma

In 1994, the "danger model" argued that adaptive immune responses are driven rather by molecules released upon tissue damage than by the recognition of "strange" molecules. Thus, an alternative to the "self versus non-self recognition model" has been provided. The model, which suggests that the immune system discriminates dangerous from safe molecules, has established the basis for the future designation of damage-associated molecular patterns (DAMPs), a term that was coined by Walter G. Land, Seong, and Matzinger. The pathological importance of DAMPs is barely somewhere else evident as in the posttraumatic or post-surgical inflammation and regeneration. Since DAMPs have been identified to trigger specific immune responses and inflammation, which is not necessarily detrimental but also regenerative, it still remains difficult to describe their "friend or foe" role in the posttraumatic immunogenicity and healing process. DAMPs can be used as biomarkers to indicate and/or to monitor a disease or injury severity, but they also may serve as clinically applicable parameters for optimized indication of the timing for, i.e., secondary surgeries. While experimental studies allow the detection of these biomarkers on different levels including cellular, tissue, and circulatory milieu, this is not always easily transferable to the human situation. Thus, in this review, we focus on the recent literature dealing with the pathophysiological importance of DAMPs after traumatic injury. Since dysregulated inflammation in traumatized patients always implies disturbed resolution of inflammation, so-called model of suppressing/inhibiting inducible DAMPs (SAMPs) will be very briefly introduced. Thus, an update on this topic in the field of trauma will be provided.

Specific targeting of IL-1β activity to CD8+ T cells allows for safe use as a vaccine adjuvant

Annual administration and reformulation of influenza vaccines is required for protection against seasonal infections. However, the induction of strong and long-lasting T cells is critical to reach broad and potentially lifelong antiviral immunity. The NLRP3 inflammasome and its product interleukin-1β (IL-1β) are pivotal mediators of cellular immune responses to influenza, yet, overactivation of these systems leads to side effects, which hamper clinical applications. Here, we present a bypass around these toxicities by targeting the activity of IL-1β to CD8+ T cells. Using this approach, we demonstrate safe inclusion of IL-1β as an adjuvant in vaccination strategies, leading to full protection of mice against a high influenza virus challenge dose by raising potent T cell responses. In conclusion, this paper proposes a class of IL-1β-based vaccine adjuvants and also provides further insight in the mechanics of cellular immune responses driven by IL-1β.

Anakinra Therapy for Non-cancer Inflammatory Diseases

Interleukin-1 (IL-1) is the prototypical inflammatory cytokine: two distinct ligands (IL-1α and IL-1β) bind the IL-1 type 1 receptor (IL-1R1) and induce a myriad of secondary inflammatory mediators, including prostaglandins, cytokines, and chemokines. IL-1α is constitutively present in endothelial and epithelial cells, whereas IL-1β is inducible in myeloid cells and released following cleavage by caspase-1. Over the past 30 years, IL-1-mediated inflammation has been established in a broad spectrum of diseases, ranging from rare autoinflammatory diseases to common conditions such as gout and rheumatoid arthritis (RA), type 2 diabetes, atherosclerosis, and acute myocardial infarction. Blocking IL-1 entered the clinical arena with anakinra, the recombinant form of the naturally occurring IL-1 receptor antagonist (IL-1Ra); IL-1Ra prevents the binding of IL-1α as well as IL-1β to IL-1R1. Quenching IL-1-mediated inflammation prevents the detrimental consequences of tissue damage and organ dysfunction. Although anakinra is presently approved for the treatment of RA and cryopyrin-associated periodic syndromes, off-label use of anakinra far exceeds its approved indications. Dosing of 100 mg of anakinra subcutaneously provides clinically evident benefits within days and for some diseases, anakinra has been used daily for over 12 years. Compared to other biologics, anakinra has an unparalleled record of safety: opportunistic infections, particularly Mycobacterium tuberculosis, are rare even in populations at risk for reactivation of latent infections. Because of this excellent safety profile and relative short duration of action, anakinra can also be used as a diagnostic tool for undefined diseases mediated by IL-1. Although anakinra is presently in clinical trials to treat cancer, this review focuses on anakinra treatment of acute as well as chronic inflammatory diseases.

Danger signals in trauma

This review summarizes a short list of currently discussed trauma-induced danger-associated molecular patterns (DAMP). Due to the bivalent character and often pleiotropic effects of a DAMP, it is difficult to describe its "friend or foe" role in post-traumatic inflammation and regeneration, both systemically as well locally in tissues. DAMP can be used as biomarkers to indicate or monitor disease or injury severity, but also may serve as clinically applicable parameters for better indication and timing of surgery. Due to the inflammatory processes at the local tissue level or the systemic level, the precise role of DAMP is not always clear to define. While in vitro and experimental studies allow for the detection of these biomarkers at the different levels of an organism-cellular, tissue, circulation-this is not always easily transferable to the human setting. Increased knowledge exploring the dual role of DAMP after trauma, and concentrating on their nuclear functions, transcriptional targets, release mechanisms, cellular sources, multiple functions, their interactions and potential therapeutic targeting is warranted.

Overview of the IL-1 family in innate inflammation and acquired immunity

The interleukin-1 (IL-1) family of cytokines and receptors is unique in immunology because the IL-1 family and Toll-like receptor (TLR) families share similar functions. More than any other cytokine family, the IL-1 family is primarily associated with innate immunity. More than 95% of living organisms use innate immune mechanisms for survival whereas less than 5% depend on T- and B-cell functions. Innate immunity is manifested by inflammation, which can function as a mechanism of host defense but when uncontrolled is detrimental to survival. Each member of the IL-1 receptor and TLR family contains the cytoplasmic Toll-IL-1-Receptor (TIR) domain. The 50 amino acid TIR domains are highly homologous with the Toll protein in Drosophila. The TIR domain is nearly the same and present in each TLR and each IL-1 receptor family. Whereas IL-1 family cytokine members trigger innate inflammation via IL-1 family of receptors, TLRs trigger inflammation via bacteria, microbial products, viruses, nucleic acids, and damage-associated molecular patterns (DAMPs). In fact, IL-1 family member IL-1a and IL-33 also function as DAMPs. Although the inflammatory properties of the IL-1 family dominate in innate immunity, IL-1 family member can play a role in acquired immunity. This overview is a condensed update of the IL-1 family of cytokines and receptors.

Cytokines of the IL-1 family: recognized targets in chronic inflammation underrated in organ transplantations

Interleukin 1 (IL-1) family is a group of cytokines with multiple local and systemic effects, which regulates both innate and adaptive immune responses. Generally, most IL-1 family cytokines express prevailing pro-inflammatory activities (IL-1α, IL-1β, IL-18, IL-33, IL-36 α, β, γ), whereas others are anti-inflammatory (IL-1Ra (IL-1 receptor antagonist), IL-36Ra, IL-38, IL-37). In addition to their immunomodulatory roles, some of them are also involved in the physiological modulation of homeostatic processes and directly affect mRNA transcription. IL-1 family cytokines bind to specific receptors composed of a ligand-binding chain and an accessory chain. The pro-inflammatory effects of IL-1 family cytokines are regulated on the level of transcription, enzymatic processing of precursors, release of soluble antagonists, and expression of decoy receptors. Members of the IL-1 family regulate the recruitment and activation of effector cells involved in innate and adaptive immunity, but they are also involved in the pathogenesis of chronic disorders, including inflammatory bowel disease, rheumatoid arthritis, and various autoimmune and autoinflammatory diseases. There are only limited data regarding the role of IL-1 cytokines in transplantation. In recent years, targeted therapeutics affecting IL-1 have been used in multiple clinical studies. In addition to the recombinant IL-1Ra, anakinra (highly effective in autoinflammatory diseases and tested for other chronic diseases), the monoclonal antibodies canakinumab, gevokizumab, and rilonacept (a long-acting IL-1 receptor fusion protein) provide further options to block IL-1 activity. Furthermore, new inhibitors of IL-18 (GSK 1070806, ABT-325, rIL-18BP (IL-18 binding protein)) and IL-33 (CNTO-7160) are presently under clinical studies and other molecules are being developed to target IL-1 family cytokines.

Potential of IL-1, IL-18 and Inflammasome Inhibition for the Treatment of Inflammatory Skin Diseases

In 2002, intracellular protein complexes known as the inflammasomes were discovered and were shown to have a crucial role in the sensing of intracellular pathogen- and danger-associated molecular patterns (PAMPs and DAMPs). Activation of the inflammasomes results in the processing and subsequent secretion of the pro-inflammatory cytokines IL-1β and IL-18. Several autoinflammatory disorders such as cryopyrin-associated periodic syndromes and Familial Mediterranean Fever have been associated with mutations of genes encoding inflammasome components. Moreover, the importance of IL-1 has been reported for an increasing number of autoinflammatory skin diseases including but not limited to deficiency of IL-1 receptor antagonist, mevalonate kinase deficiency and PAPA syndrome. Recent findings have revealed that excessive IL-1 release induced by harmful stimuli likely contributes to the pathogenesis of common dermatological diseases such as acne vulgaris or seborrheic dermatitis. A key pathogenic feature of these diseases is IL-1β-induced neutrophil recruitment to the skin. IL-1β blockade may therefore represent a promising therapeutic approach. Several case reports and clinical trials have demonstrated the efficacy of IL-1 inhibition in the treatment of these skin disorders. Next to the recombinant IL-1 receptor antagonist (IL-1Ra) Anakinra and the soluble decoy Rilonacept, the anti-IL-1α monoclonal antibody MABp1 and anti-IL-1β Canakinumab but also Gevokizumab, LY2189102 and P2D7KK, offer valid alternatives to target IL-1. Although less thoroughly investigated, an involvement of IL-18 in the development of cutaneous inflammatory disorders is also suspected. The present review describes the role of IL-1 in diseases with skin involvement and gives an overview of the relevant studies discussing the therapeutic potential of modulating the secretion and activity of IL-1 and IL-18 in such diseases.

T Cell Production of IFNγ in Response to TLR7/IL-12 Stimulates Optimal B Cell Responses to Viruses

Knowledge of the processes that underlie IgG subclass switching could inform strategies designed to counteract infections and autoimmunity. Here we show that TLR7 ligands induce subsets of memory CD4 and CD8 T cells to secrete interferon γ (IFNγ) in the absence of antigen receptor stimulation. In turn, TLR ligation and IFNγ cause B cells to express the transcription factor, T-bet, and to switch immunoglobulin production to IgG2a/c. Absence of TLR7 in T cells leads to the impaired T-bet expression in B cells and subsequent inefficient IgG2a isotype switching both in vitro and during the infection with Friend virus in vivo. Our results reveal a surprising mechanism of antiviral IgG subclass switching through T-cell intrinsic TLR7/IL-12 signaling.

Review: Infection, fever, and exogenous and endogenous pyrogens: some concepts have changed

For many years, it was thought that bacterial products caused fever via the intermediate production of a host-derived, fever-producing molecule, called endogenous pyrogen (EP). Bacterial products and other fever-producing substances were termed exogenous pyrogens. It was considered highly unlikely that exogenous pyrogens caused fever by acting directly on the hypothalamic thermoregulatory center since there were countless fever-producing microbial products, mostly large molecules, with no common physical structure. In vivo and in vitro, lipopolysaccharides (LPSs) and other microbial products induced EP, subsequently shown to be interleukin-1 (IL-1). The concept of the `endogenous pyrogen' cause of fever gained considerable support when pure, recombinant IL-1 produced fever in humans and in animals at subnanomolar concentrations. Subsequently, recombinant tumor necrosis factor-α (TNF-α), IL-6 and other cytokines were also shown to cause fever and EPs are now termed pyrogenic cytokines. However, the concept was challenged when specific blockade of either IL-1 or TNF activity did not diminish the febrile response to LPS, to other microbial products or to natural infections in animals and in humans. During infection, fever could occur independently of IL-1 or TNF activity. The cytokine-like property of Toll-like receptor (TLR) signal transduction provides an explanation by which any microbial product can cause fever by engaging its specific TLR on the vascular network supplying the thermoregulatory center in the anterior hypothalamus. Since fever induced by IL-1, TNF-α, IL-6 or TLR ligands requires cyclooxygenase-2, production of prostaglandin E2 (PGE 2) and activation of hypothalamic PGE2 receptors provides a unifying mechanism for fever by endogenous and exogenous pyrogens. Thus, fever is the result of either cytokine receptor or TLR triggering; in autoimmune diseases, fever is mostly cytokine mediated whereas both cytokine and TLR account for fever during infection.

The IL-1 cytokine family and its role in inflammation and fibrosis in the lung

The IL-1 cytokine family comprises 11 members (7 ligands with agonist activity, 3 receptor antagonists and 1 anti-inflammatory cytokine) and is recognised as a key mediator of inflammation and fibrosis in multiple tissues including the lung. IL-1 targeted therapies have been successfully employed to treat a range of inflammatory conditions such as rheumatoid arthritis and gouty arthritis. This review will introduce the members of the IL-1 cytokine family, briefly discuss the cellular origins and cellular targets and provide an overview of the role of these molecules in inflammation and fibrosis in the lung.

The history of fever, leukocytic pyrogen and interleukin-1

There has been great progress in the 30 y since the reporting in 1984 of the cDNA for interleukin1 (IL1) β in the human and IL1α in the mouse. However, the history of IL1 begins in the early 1940s with investigations into the nature of an endogenous fever-producing protein released rabbit peritoneal neutrophils. Most researchers in immunology today are unaware that the field of cytokines, particularly the field of inflammatory cytokines. Toll-like receptors and innate immunity traces back to studies on fever. Researchers in infectious diseases wanted to know about an endogenous protein that caused fever, independent of infection. The endogenous fever-producing protein was called by various names: granulocyte, endogenous or leukocytic pyrogen. It is a fascinating and sometimes controversial story for biology and medicine and for the treatment of inflammatory diseases. Few imagined that this fever-producing protein would play such a major role in nearly every cell and in most diseases. This paper reviews the true background and milestones of interleukin1 from the purification of leukocytic pyrogen to the first cDNA of IL1β and the validation of cytokine biology from ill-defined factors to its present day importance.

30 years hids-Travels between bedside and bench

In this paper I describe more than 30 years of investigations of the autoinflammatory syndrome hyper-IgD syndrome (HIDS). In the first paper after the recognition of the syndrome published in 1984, we described the characteristics of this periodic fever syndrome. The hypotheses regarding the pathogenesis of the fever and the acute phase response in these patients prompted us to study interleukin-1 (IL-1), the cytokine formerly described as endogenous pyrogen and lymphocyte activating factor. Although we were unable to find elevated concentrations of IL-1 in the circulation, we discovered that white blood cells spontaneously produced elevated amounts of IL-1b. A major next discovery was the identification of the gene defect by us and others in 1999: quite unexpectedly the mevalonate kinase, an enzyme in the cholesterol synthesis pathway was found to be mutated. We were able to describe a founder effect and a phenotypic continuum with the classical mevalonate aciduria in the years to follow. A major step forward was the finding that recombinant interleukin-1 receptor antagonist (anakinra) was an effective treatment for the majority of patients. Thus, research over a period of three decades after the first recognition of the syndrome, has yielded much insight into the pathogenesis as well as an effective therapy for HIDS.

How is inflammation initiated? Individual influences of IL-1, IL-18 and HMGB1

Pro-inflammatory cytokines are crucial for fighting infection and establishing immunity. Recently, other proteins, such as danger-associated molecular patterns (DAMPs), have also been appreciated for their role in inflammation and immunity. Following the formation and activation of multiprotein complexes, termed inflammasomes, two cytokines, IL-1β and IL-18, along with the DAMP High Mobility Group Box 1 (HMGB1), are released from cells. Although these proteins all lack classical secretion signals and are released by inflammasome activation, they each lead to different downstream consequences. This review examines how various inflammasomes promote the release of IL-1β, IL-18 and HMGB1 to combat pathogenic situations. Each of these effector molecules plays distinct roles during sterile inflammation, responding to viral, bacterial and parasite infection, and tailoring the innate immune response to specific threats.

Interleukin-1β in innate inflammation, autophagy and immunity

Although IL-1β is the master inflammatory cytokine in the IL-1 family, after more than ten years of continuous breeding, mice deficient in IL-1β exhibit no spontaneous disease. Therefore, one concludes that IL-1β is not needed for homeostasis. However, IL-1β-deficient mice are protected against local and systemic inflammation due to live infections, autoimmune processes, tumor metastasis and even chemical carcinogenesis. Based on a large number of preclinical studies, blocking IL-1β activity in humans with a broad spectrum of inflammatory conditions has reduced disease severity and for many, has lifted the burden of disease. Rare and common diseases are controlled by blocking IL-1β. Immunologically, IL-1β is a natural adjuvant for responses to antigen. Alone, IL-1β is not a growth factor for lymphocytes; rather in antigen activated immunocompetent cells, blocking IL-1 reduces IL-17 production. IL-1β markedly increases in the expansion of naive and memory CD4T cells in response to challenge with their cognate antigen. The response occurs when only specific CD4T cells respond to IL-1β and not to IL-6 or CD-28. A role for autophagy in production of IL-1β has emerged with deletion of the autophagy gene ATG16L1. Macrophages from ATG16L1-deficient mice produce higher levels of IL-1β after stimulation with TLR4 ligands via a mechanism of caspase-1 activation. The implications for increased IL-1β release in persons with defective autophagy may have clinical importance for disease.

A clinical perspective of IL-1β as the gatekeeper of inflammation

An expanding spectrum of acute and chronic non-infectious inflammatory diseases is uniquely responsive to IL-1β neutralization. IL-1β-mediated diseases are often called "auto-inflammatory" and the dominant finding is the release of the active form of IL-1β driven by endogenous molecules acting on the monocyte/macrophage. IL-1β activity is tightly controlled and requires the conversion of the primary transcript, the inactive IL-1β precursor, to the active cytokine by limited proteolysis. Limited proteolysis can take place extracellularly by serine proteases, released in particular by infiltrating neutrophils or intracellularly by the cysteine protease caspase-1. Therefore, blocking IL-1β resolves inflammation regardless of how the cytokine is released from the cell or how the precursor is cleaved. Endogenous stimulants such as oxidized fatty acids and lipoproteins, high glucose concentrations, uric acid crystals, activated complement, contents of necrotic cells, and cytokines, particularly IL-1 itself, induce the synthesis of the inactive IL-1β precursor, which awaits processing to the active form. Although bursts of IL-1β precipitate acute attacks of systemic or local inflammation, IL-1β also contributes to several chronic diseases. For example, ischemic injury, such as myocardial infarction or stroke, causes acute and extensive damage, and slowly progressive inflammatory processes take place in atherosclerosis, type 2 diabetes, osteoarthritis and smoldering myeloma. Evidence for the involvement of IL-1β and the clinical results of reducing IL-1β activity in this broad spectrum of inflammatory diseases are the focus of this review.

Interleukin-1 in the pathogenesis and treatment of inflammatory diseases

More than any other cytokine family, the IL-1 family of ligands and receptors is primarily associated with acute and chronic inflammation. The cytosolic segment of each IL-1 receptor family member contains the Toll-IL-1-receptor domain. This domain is also present in each Toll-like receptor, the receptors that respond to microbial products and viruses. Since Toll-IL-1-receptor domains are functional for both receptor families, responses to the IL-1 family are fundamental to innate immunity. Of the 11 members of the IL-1 family, IL-1β has emerged as a therapeutic target for an expanding number of systemic and local inflammatory conditions called autoinflammatory diseases. For these, neutralization of IL-1β results in a rapid and sustained reduction in disease severity. Treatment for autoimmune diseases often includes immunosuppressive drugs whereas neutralization of IL-1β is mostly anti-inflammatory. Although some autoinflammatory diseases are due to gain-of-function mutations for caspase-1 activity, common diseases such as gout, type 2 diabetes, heart failure, recurrent pericarditis, rheumatoid arthritis, and smoldering myeloma also are responsive to IL-1β neutralization. This review summarizes acute and chronic inflammatory diseases that are treated by reducing IL-1β activity and proposes that disease severity is affected by the anti-inflammatory members of the IL-1 family of ligands and receptors.

Blocking interleukin-1β in acute and chronic autoinflammatory diseases

An expanding spectrum of acute and chronic inflammatory diseases is considered 'autoinflammatory' diseases. This review considers autoinflammatory diseases as being distinct from 'autoimmune' diseases. Autoimmune diseases are associated with dysfunctional T cells and treated with 'biologicals', including antitumour necrosis factorα, CTLA-Ig, anti-IL-12/23, anti-CD20, anti-IL-17 and anti-IL-6 receptor. In contrast, autoinflammatory diseases are uniquely attributed to a dysfunctional monocyte caspase 1 activity and secretion of IL-1β; indeed, blocking IL-1β results in a rapid and sustained reduction in the severity of most autoinflammatory diseases. Flares of gout, type 2 diabetes, heart failure and smouldering multiple myeloma are examples of seemingly unrelated diseases, which are uniquely responsive to IL 1β neutralization.

IL-1: discoveries, controversies and future directions

Although there has been a great amount of progress in the 25 years since the first reporting of the cDNA for IL-1alpha and IL-1beta, the history of IL-1 goes back to the early 1940s. In fact, the entire field of inflammatory cytokines, TLR and the innate immune response can be found in the story of IL-1. This Viewpoint follows the steps from the identification of the fever-inducing activities of "soluble factors" produced by endotoxin-stimulated leukocytes through to the discovery of cryopyrin and the caspase-1 inflammasome and on to the clinical benefits of anti-IL-1beta-based therapeutics. It also discusses some of the current controversies regarding the activation of the inflammasome. The future of novel anti-inflammatory agents to combat chronic inflammation is based, in part, on the diseases that are uniquely responsive to anti-IL-1beta, which is surely a reason to celebrate the 25th anniversary of the cloning of IL-1alpha and IL-1beta.

Historical insights into cytokines

Cytokines affect nearly every biological process; these include embryonic development, disease pathogenesis, non-specific response to infection, specific response to antigen, changes in cognitive functions and progression of the degenerative processes of aging. In addition, cytokines are part of stem cell differentiation, vaccine efficacy and allograft rejection. This short insight focuses on the milestones in cytokine biology and how the various and often contradictory activities of these small, non-structural proteins affected the fields of inflammation and immunology. Multiple biological properties or pleiotropism is the hallmark of a cytokine. Today, the term "cytokine" encompasses interferons, the interleukins, the chemokine family, mesenchymal growth factors, the tumor necrosis factor family and adipokines. As of this writing, 33 cytokines are called interleukins, but many are part of families of related but distinct gene products. There are certainly over 100 separate genes coding for cytokine-like activities, many with overlapping functions and many still unexplored. Also discussed in this overview are the failures and successes of cytokines as therapeutic targets. A recent advance in the field has been that of differential cytokine production, which can be used to classify human disease as being "autoimmune" or "autoinflammatory" thus impacting on therapeutic interventions.

Cytokines: past, present, and future

This review provides an historical account of the discovery and development of cytokines. Cytokines are soluble extracellular proteins or glycoproteins that are crucial intercellular regulators and mobilizers of cells engaged in innate as well as adaptive inflammatory host defenses, cell growth, differentiation, cell death, angiogenesis, and development and repair processes aimed at the restoration of homeostasis. Although cytokines are occasionally produced constitutively, they are usually produced by virtually every nucleated cell type in response to injurious stimuli. Cytokines act on cells expressing complementary receptors. Cytokines have been assigned to various family groups based on the structural homologies of their receptors. This review shows how cytokine research evolved from phenomenological to molecular stages and from a focus on ligands to characterization of cytokine receptors. The advent of molecular biology, monoclonal antibodies, and microsequencing made it possible to obtain pure recombinant cytokine preparation for experimental and therapeutic applications. The development of targeted gene deletions revealed many cytokines to have unexpected pathophysiological functions. The identification of "virokines," homologues that mimic cytokine ligands and receptors, has provided impetus to the founding of biotechnology companies aimed at developing cytokine agonists and antagonists for therapeutic applications. The discipline of cytokinology is now endowed with several journals, multiple annual meetings, and many devoted investigators. The explosion in cytokine information over the past 40 years has been enormous and full of surprises. If past be prologue, with the advent of genomics and proteomics the future should witness even greater progress.

Macrophage- and neutrophil-dominant arthritis in human IL-1 alpha transgenic mice

To study the effects of IL-1 alpha in arthritis, we generated human IL-1 alpha (hIL-1 alpha). Transgenic mice expressed hIL-1 alpha mRNA in various organs, had high serum levels of hIL-1 alpha, and developed a severe polyarthritic phenotype at 4 weeks of age. Not only bone marrow cells but also synoviocytes from knee joints produced biologically active hIL-1 alpha. Synovitis started 2 weeks after birth, and 8-week-old mice showed hyperplasia of the synovial lining layer, the formation of hyperplastic synovium (pannus) and, ultimately, destruction of cartilage. Hyperplasia of the synovial lining was due to the accumulation of macrophage-like cells expressing F4/80 molecules. hIL-1 alpha was widely distributed in macrophage- and fibroblast-like cells of the synovial lining cells, as well as synovial fluid monocytes. T and B cells were rare in the synovial fluid, and analysis of marker expression suggests that synoviocytes were directly histolytic and did not act as antigen-presenting cells. In the joints of these mice, we found elevated levels of cells of the monocyte/macrophage and granulocyte lineages and of polymorphonuclear neutrophils (PMNs), most of which expressed Gr-1, indicating that they were mature, tissue-degrading PMNS: Cultured synoviocytes and PMNs from these animals overexpress GM-CSF, suggesting that the hematopoietic changes induced by IL-1 and the consequent PMN activation and joint destruction are mediated by this cytokine.

Thermoregulation and the pathogenesis of fever

Infections, trauma, inflammatory processes, and some malignant diseases induce a constellation of host responses that are collectively referred to as the "acute-phase response." Elevation of core temperature is certainly part of the acute-phase response, and cytokines that raise core temperature in pathologic states are some of the same cytokines that account for other manifestations of the acute-phase response. This article examines fever as a part of the acute-phase reaction and the role of cytokines in thermoregulation.

Benefits of posttransplantation monitoring of interleukin 6 in lung transplantation

To determine the predictive diagnostic value of interleukin 6 (IL-6) monitoring in lung and heart-lung transplants, we measured posttransplantation serum IL-6 levels in 17 adult lung or heart-lung transplant recipients. Posttransplantation IL-6 elevation patterns were classified into 4 groups: serum IL-6 level remained negative throughout the monitoring period (group 1; n = 1; 6%); several sharp spikes with normal baseline (group 2; n = 9; 53%); persistently high level of serum IL-6 (group 3; n = 3; 18%); and several sharp spikes of serum IL-6 elevation with abnormally high baseline (group 4; n = 4; 24%). One patient without an elevation of IL-6 (group 1) did not experience any episodes of rejection or infection. Nine patients in group 2 had 19 IL-6 spikes, 13 of which were associated with histopathologically or clinically diagnosed rejection, 3 with acute bronchitis, and 1 with diffuse alveolar damage. Three patients in group 3 had persistent infections including cytomegalovirus infection, toxic megacolon, and repeated bacterial infection during the monitoring period, and 4 in group 4 died within 3 months after transplantation. From this study it appears that a spiked elevation of IL-6 could have a predictive value in diagnosing rejection, and persistently high levels of IL-6 indicate the presence of infection. Thus, IL-6 monitoring is beneficial for lung transplant recipients.

Purification of interleukin-1 beta converting enzyme, the protease that cleaves the interleukin-1 beta precursor

We have purified the IL-1 beta converting enzyme from the THP-1 cell line using standard chromatographic techniques and obtained the N-terminal amino acid sequence of this novel protein. After stimulation of THP-1 cells with lipopolysaccharide, hydroxyurea, and silica, the protease was solubilized by multiple freeze/thawing. The protein was purified by ion-exchange chromatography, affinity chromatography on blue agarose, gel filtration, and chromatofocusing. The molecular weight of the protein is approximately 22,000 Da and the pI is between 7.1 and 6.8. The overall yield for this procedure was 16% of the activity found in the initial cell lysates. An antiserum raised against a peptide based on the N-terminus was used to precipitate the protease, confirming our identification of the 22,000-Da protein as the IL-1 beta converting enzyme.

Restricted secretion of a T-lymphocyte chemotactic cytokine by serotonin-stimulated cultured aortic endothelial cells

The diversity of biologically active molecules produced by vascular endothelium suggests that the endothelial cell is an active participant in numerous physiological responses, including those of the immune system. In fact, the accumulation of T lymphocytes at extralymphatic inflammatory foci represents a series of interactions between lymphocytes and vascular endothelial cells. These interactions, however, may be modulated by other factors, such as vasoactive amines. In the current study, we report that serotonin-stimulated cultured bovine aortic endothelial cells (BAECs) secrete a T-lymphocyte chemotactic cytokine (endothelial cell-derived lymphocyte chemotactic activity [ED-LCA]). Supernatants from BAECs incubated with 10(-7)-10(-4) M serotonin (5-hydroxytryptamine [5-HT]) enhanced T-cell migration, which peaked at 10(-5) M 5-HT (235 +/- 18% control migration). ED-LCA was not stored in an active form in BAECs; its secretion occurred within 60 minutes of exposure to 5-HT and was blocked by two different 5-HT2 receptor antagonists. ED-LCA was not secreted after exposure of BAECs to histamine or angiotensin II, nor was it secreted by either 5-HT-stimulated bovine pulmonary arterial or human umbilical vein endothelial cells. Physicochemical characterization of ED-LCA demonstrated that it was a trypsin-sensitive protein with an apparent molecular mass of 13-15 kDa. Preparative isoelectric focusing demonstrated pIs of 6.0 and 7.5. When applied to a molecular sieve column, the chemotactic activity corresponding to these pIs eluted in the region of 13-15 kDa. Further investigation demonstrated that partially purified ED-LCA was specific for CD4+ and CD8+ T-lymphocyte subsets and did not enhance the migration of neutrophils or monocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

T lymphocyte stress response. I. Induction of heat shock protein synthesis at febrile temperatures is correlated with enhanced resistance to hyperthermic stress but not to heavy metal toxicity or dexamethasone-induced immunosuppression

We have investigated the effect of febrile temperatures (less than or equal to 41 degrees C) on T cell heat shock protein (hsp) synthesis and the acquisition of stress tolerance. Enhanced synthesis of hsps was detected in highly purified T cells and two cloned T cell lines representing helper T (D10) and cytotoxic T cell (Qa-2 128.38) subsets at temperatures as low as 39 degrees C with a maximal response at 41 degrees C. Three major hsps with approximate molecular weights of 110, 90, and 75 were detected in these T cell populations. Western blot analysis using a monoclonal antibody specific for hsp70 indicated that the 75-kDa protein represented hscp70, the cognate or constitutively produced member of the hsp70 family. Although the strongly heat-inducible hsp70 could not be detected in T cells incubated at 41 degrees C by immunoblot analysis, two-dimensional SDS-PAGE analysis did detect a modest induction of hsp70. Thus, hscp70 and not hsp70 was the major intracellular hsp70 member in T cells incubated at febrile temperatures. Enhanced hsp synthesis reflected augmented transcription of hsp genes which was contingent on the continued presence of hyperthermic stress. In order to determine whether induction of hsp synthesis conferred a state of increased resistance to thermal stress, splenic T cells were incubated at either 37 degrees or 41 degrees C (induction temperatures) and then subjected to a heat-shock challenge temperature. These studies revealed that following heat-shock challenge, mitogen-stimulated T cells preincubated at 41 degrees C synthesized DNA at an enhanced rate relative to controls (induction temperature, 37 degrees C). Thus, febrile temperatures were capable of inducing a state of acquired thermotolerance in T cells. However, the thermotolerant state did not protect T cell proliferation against other unrelated stressors such as cadmium and dexamethasone. Reconstitution experiments with accessory cells and interleukin-2-containing supernatants failed to reveal enhanced resistance in thermotolerant T cells to cadmium toxicity or the immunosuppressive activities of dexamethasone. The possibility that higher intracellular concentrations of hsps are required to demonstrate protection against these stressors was tested by the concurrent exposure of T cells to a febrile temperature (41 degrees C) and ethanol. This resulted in a synergistic increase in hsp90 and hsp70 synthesis; however, there was no evidence of enhanced resistance to cadmium- or dexamethasone-induced stress in T cells given this induction protocol. Similarly, alloreactive cytotoxic T lymphocyte responses were inhibited to the same extent in both control and thermotolerant T cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Fever induced by Escherichia coli or intrahypothalamic prostaglandin E2 enhances interferon-gamma synthesis

We previously showed that hyperthermia induced in rhesus monkeys (Macaca mulatta) by forced passive heating "primes" the peripheral lymphocyte population for increased synthesis of interferon-gamma (IFN-gamma). It was not clear whether these data could be extrapolated to the physiological response in naturally occurring fever. Therefore, in the current experiments, the temperature of rhesus monkeys was raised either by systemic injection of killed Escherichia coli or by intrahypothalamic administration of prostaglandin E2. Mononuclear cells collected subsequently from such monkeys produced more IFN-gamma in response to stimulation with mitogens than cells from control monkeys. Direct administration of IFN-alpha, -beta, or -gamma to the hypothalamus did not affect the body temperature of rhesus monkeys.

Dynamic changes in soluble interleukin-2 receptor levels after lung or heart-lung transplantation

Activation of T-lymphocytes is accompanied by the release of interleukin-2 receptors (IL-2R) in a soluble form that can be measured as an index of the activation process. We performed a prospective, blinded study of the dynamic changes in soluble IL-2R levels in serum in 12 patients undergoing lung or heart-lung transplantation. The levels of soluble IL-2R were markedly elevated during episodes of rejection (geometric mean value X divided by SEM = 3,770 X divided by 1.06 versus 411 X divided by 1.08 U/ml for normal controls, p less than 0.0001). Levels of soluble IL-2R were 2,105 X divided by 1.16 U/ml with rejection episodes in single lung recipients versus 5,560 X divided by 1.30 in recipients of two lungs (p = 0.005). Soluble IL-2R levels were 1,468 X divided by 1.05 during episodes of nonbacterial infections, 1,879 X divided by 1.34 with bacterial infections, and 5,056 X divided by 1.08 with sepsis (p less than 0.001 for each category compared to normals). Levels of soluble IL-2R exceeded 6,750 U/ml only with rejection episodes and were greater than 4,100 U/ml either with rejection, clinical sepsis, or overwhelming bacterial infection. We conclude that marked elevations of soluble IL-2R are associated with rejection, intermediate elevations with either rejection or infection, and that low levels of soluble IL-2R exclude rejection.

The biological activities of interleukin-1

Interleukin-1 (IL-1) refers to a hormone-like polypeptide that mediates a broad spectrum of activities in host defence as well as a variety of disease processes. Originally described as a substance produced by activated macrophages, IL-1 is now recognized as a polypeptide produced by many other cell types. Two distinct genes have been identified that code for two structurally related forms of the molecule, termed IL-1 alpha and beta. IL-1 is the primary mediator of the acute phase response and is responsible for many of the changes associated with the onset of infection. It is involved in the immune response to antigenic challenge. IL-1 induces fever and has profound endocrinologic, neurologic, metabolic and hematologic effects. Both forms of IL-1 bind to a common receptor that has been identified on a variety of cell types including lymphocytes, hepatocytes, endothelial cells and fibroblasts. Many of the activities of IL-1 are mediated by the induction of other cytokines like IL-2, IL-6, interferons, tumor necrosis factor, and colony-stimulating factors. In animals IL-1 protects against the effects of radiation, it enhances natural resistance of infection, and it stimulates bone marrow recovery after myelosuppression. These studies suggest that IL-1 may be used as a therapeutic agent.

Preparation and application of polyclonal antibodies to recombinant human interleukin-1 alpha and interleukin-1 beta

We report the preparation and application of polyclonal antisera to the analysis and quantitation of human interleukin-1 alpha (IL-1 alpha) and human interleukin-1 beta (IL-1 beta). The anti IL-1 alpha antibodies specifically react with the alpha form of IL-1 and do not cross react (less than 0.1%) with the beta form of IL-1 and vice versa. Data reported here demonstrate that detection of human IL-1 alpha or beta by a radioimmunoassay technique is sensitive enough to measure picogram levels of these lymphokines. The practical application of using these highly specific antisera for radioimmunoassays was established by measuring exogenously added IL-1 alpha or IL-1 beta to human plasma. Potential benefits of these reagents and the radioimmunoassay procedures described herein are discussed in relation to the biological assays which cannot distinguish between human IL-1 alpha and human IL-1 beta.

Attenuation of the febrile response in guinea pigs by fish oil enriched diets

The influence of dietary lipid manipulation on the fever response to an injection of murine recombinant Interleukin-1 (rIL-1) in guinea pigs was examined. The animals were fed diets identical except for the lipid source for periods of 5 and 6 wk. In vitro thromboxane B2/B3 (TxB2/B3) production in collagen-stimulated whole blood was also measured. One diet was enriched with menhaden oil, high in the omega-3 series of fatty acids. The other diet contained safflower oil, consisting primarily of the omega-6 fatty acid linoleic acid (74%). Animals fed the fish oil-enriched diet for 6 wk not 5 week had a blunted fever response after rIL-1 injection. This was associated with a 27% increase (p less than 0.05) in total omega-3 fatty acids in plasma phospholipids between weeks 5 and 6 in fish oil-fed animals. Safflower oil-fed animals produced a "normal" febrile response regardless of the duration of feeding. Safflower-fed guinea pigs demonstrated a significant increase in TxB2/B3 production in whole blood after 6 wks that was associated with a 25% increase (p less than 0.05) in plasma phospholipid arachidonic acid levels between weeks 5 and 6. Despite significant reductions in phospholipid linoleic acid in animals fed fish oil, arachidonic acid levels remained unchanged. In the guinea pig model used, long-term menhaden oil feeding can significantly blunt the febrile response induced by exogenous Interleukin-1. Also, a high intake of linoleic acid as seen in safflower oil feeding can significantly increase thromboxane production in stimulated whole blood.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin-1 production in acute viral hepatitis

The in vitro production of interleukin-1 in 15 children with acute hepatitis A and five children with acute hepatitis B was determined by measuring lymphocyte activating factor secreted by peripheral blood monocytes in a thymocyte proliferation assay. Aluminium hydroxide induced production of lymphocyte activating factor was significantly lower in patients with acute hepatitis A as well as patients with hepatitis B as compared with healthy control subjects. In both forms of acute viral hepatitis production of lymphocyte activating factor was severely depressed during the first week, increased gradually during the further course of the illness, but did not reach normal concentrations within the first three weeks after onset of the acute symptoms of the disease. No correlation could be found between in vitro production of lymphocyte activating factor and the severity of liver disease as estimated by the rise of serum concentrations of transaminases, bilirubin, or several parameters of acute phase reaction (alpha 1 antitrypsin, C reactive protein, erythrocyte sedimentation rate). The reduced production of interleukin-1, as assessed by determination of lymphocyte activating factor, could explain the only moderate acute phase reaction seen during acute viral hepatitis.

Recombinant human interleukin 1 alpha is cytotoxic for and increases surface expression of HLA-A,B,C antigens of a human hepatoma cell line, PLC/PRF/5

Our study was undertaken to determine whether human recombinant interleukin 1 alpha (rIL 1 alpha) has any effect on the proliferation and expression of HLA-A,B,C antigens of human liver cell lines. The addition of rIL 1 alpha reduced the cell number of the human hepatoma cell line, PLC/PRF/5. This effect was determined to be cytotoxic, but not growth inhibitory, rIL 1 alpha did not change the number of Chang cell or SK-Hep-1 at a concentration as, high as 25,000 U/ml. rIL 1 alpha enhanced the expression of HLA-A,B,C antigens on PLC/PRF/5, but had no effect on Change cell or SK-Hep-1. Receptor binding studies showed that 125I-rIL 1 alpha bound to PLC/PRF/5 in a specific and saturable manner, but did not bind to Chang cell or SK-Hep-1. Scatchard plot analysis of the binding to PLC/PRF/5 revealed a single type of high affinity binding site with an apparent dissociation constant of approximately 5 x 10(-5) M and the presence of approximately 150 binding sites per cell. These findings suggest that IL 1 alpha may play a role in host defense against some hepatomas as cytotoxic factor and may be an enhancer of expression of HLA-A,B,C antigens on tumor cells.

Interleukin-1

IL-1 is a polypeptide product of various cells that mediates several components of the acute-phase response to infection and injury. Its most dramatic biological property is its ability to induce arachidonate metabolites in a variety of cells including PGE in the brain, fibroblasts, synovial cells, and chondrocytes; in addition, IL-1 induces lipoxygenase products in lymphocytes and other cells. IL-1 has been cloned. There are two forms. The predominant form of IL-1 from human monocytes has a pI of 7 (also called beta) and is initially synthesized as a precursor molecule (31 kD). A minor form (less than 100-fold) also exists (pI 5, also called alpha). IL-1 seems unique among the lymphokines and monokines in that there is no signal peptide sequence for cleavage. Depending on the stimulus, intracellular levels of precursor IL-1 can be high, whereas some cell activators result in large amounts of processed IL-1. Precursor IL-1 is cleaved into a 17.5-kD peptide, which is the predominant extracellular form. IL-1 induces prostaglandins and lymphocyte activation as well as many different biological activities. These include fever, PGE production, protease release from synovial cells and chondrocytes, bone resorption, acute-phase protein synthesis, and other effects. Although there are few studies showing an IL-1 effect on the gastrointestinal tract, the multiple biological properties of IL-1 suggest that IL-1 plays a role in inflammatory bowel disease as well as in mediating some of the gastrointestinal changes observed in systemic acute-phase responses.

The effect of interleukin 1 on IgG synthesis in systemic lupus erythematosus

The influence of interleukin 1 (IL-1) on IgG synthesis was studied in patients with systemic lupus erythematosus (SLE). Spontaneous IgG synthesis was assessed by culturing peripheral blood mononuclear cells in media for 7 days. The effect of adherent cell supernatants (ACS) on spontaneous IgG synthesis was also assessed, based upon previous studies showing that ACS contributes significantly more to IgG synthesis in SLE than it does in normals. Antiserum against IL-1 reduced spontaneous IgG synthesis by approximately 90% in SLE and normal mononuclear cell cultures. The antiserum caused a parallel reduction in the number of Ig-secreting B cells. Adsorption of SLE ACS with Sepharose-bound antiserum against IL-1 prevented ACS-induced increases in IgG synthesis. Affinity-purified or recombinant IL-1 added to media did not significantly stimulate IgG synthesis. Incubation of ACS with a monoclonal antibody against interferon-gamma had no effect on IgG synthesis, and no detectable interferon activity was found in ACS using a virus inhibition assay. Stimulation of IgG production by autologous mononuclear cell supernatants correlated directly with the presence of clinically active disease, suggesting that these in vitro observations may be important to the disease process. These findings demonstrate that hyperactive B cells from patients with SLE are regulated by factors released by adherent mononuclear cells, probably monocytes. The presence of IL-1 is crucial, but may not be sufficient, for spontaneous and ACS-induced IgG synthesis. Inhibiting or blocking the production of IL-1 may provide a means of reducing abnormal immunoglobulin synthesis in SLE.

Corticotropin-releasing factor-producing neurons in the rat activated by interleukin-1

Intraperitoneal administration of human recombinant interleukin-1 (IL-1) to rats can increase blood levels of corticosterone and adrenocorticotropic hormone (ACTH). The route by which IL-1 affects pituitary-adrenal activity is unknown. That the IL-1-induced pituitary-adrenal activation involves an increased secretion of corticotropin-releasing factor (CRF) is indicated by three lines of evidence. First, immunoneutralization of CRF markedly attenuated the IL-1-induced increase of ACTH blood levels. Second, after blockade of fast axonal transport in hypothalamic neurons by colchicine, IL-1 administration decreased the CRF immunostaining in the median eminence, indicating an enhanced release of CRF in response to IL-1. Third, IL-1 did not stimulate ACTH release from primary cultures of anterior pituitary cells. These data further support the notion of the existence of an immunoregulatory feedback circuit between the immune system and the brain.