Deubiquitination of NLRP6 inflammasome by Cyld critically regulates intestinal inflammation.

The inflammasome NLRP6 plays a crucial role in regulating inflammation and host defense against microorganisms in the intestine. However, the molecular mechanisms by which NLRP6 function is inhibited to prevent excessive inflammation remain unclear. Here, we demonstrate that the deubiquitinase Cyld prevents excessive interleukin 18 (IL-18) production in the colonic mucosa by deubiquitinating NLRP6. We show that deubiquitination inhibited the NLRP6-ASC inflammasome complex and regulated the maturation of IL-18. Cyld deficiency in mice resulted in elevated levels of active IL-18 and severe colonic inflammation following Citrobacter rodentium infection. Further, in patients with ulcerative colitis, the concentration of active IL-18 was inversely correlated with CYLD expression. Thus, we have identified a novel regulatory mechanism that inhibits the NLRP6-IL-18 pathway in intestinal inflammation.

IL-18 and infections: Is there a role for targeted therapies?

Interleukin (IL)-18 is a pro-inflammatory cytokine belonging to the IL-1 family, first identified for its interferon-γ-inducing properties. IL-18 regulates both T helper (Th) 1 and Th2 responses. It acts synergistically with IL-12 in the Th1 paradigm, whereas with IL-2 and without IL-12 it can induce Th2 cytokine production from cluster of differentation (CD)4+ T cells, natural killer (NK cells, NKT cells, as well as from Th1 cells. IL-18 also plays a role in the hemophagocytic lymphohistiocytosis, a life-threatening condition characterized by a cytokine storm that can be secondary to infections. IL-18-mediated inflammation was largely studied in animal models of bacterial, viral, parasitic, and fungal infections. These studies highlight the contribution of either IL-18 overproduction by the host or overresponsiveness of the host to IL-18 causing an exaggerated inflammatory burden and leading to tissue injury. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the coronavirus disease 2019 (COVID-19). The damage in the later phase of the disease appears to be driven by a cytokine storm, including interleukin IL-1 family members and secondary cytokines like IL-6. IL-18 may participate in this hyperinflammation, as it was previously found to be able to cause injury in the lung tissue of infected animals. IL-18 blockade has become an appealing therapeutic target and has been tested in some IL-18-mediated rheumatic diseases and infantile-onset macrophage activation syndrome. Given its role in regulating the immune response to infections, IL-18 blockade might represent a therapeutic option for COVID-19, although further studies are warranted to investigate more in detail the exact role of IL-18 in SARS-CoV-2 infection.

Anticytokine Agents: Targeting Interleukin Signaling Pathways for the Treatment of Atherothrombosis

The recognition that atherosclerosis is a complex chronic inflammatory disorder mediated through both adaptive and innate immunity has led to the hypothesis that anticytokine therapies targeting specific IL (interleukin) signaling pathways could serve as powerful adjuncts to lipid lowering in the prevention and treatment of cardiovascular disease. Cytokines involved in human atherosclerosis can be broadly classified as proinflammatory and proatherogenic (such as IL-1, IL-6, and TNF [tumor necrosis factor]) or as anti-inflammatory and antiatherogenic (such as IL-10 and IL-1rA). The recent CANTOS (Canakinumab Anti-Inflammatory Thrombosis Outcomes Study) has shown that specific targeting of IL-1ß can significantly reduce cardiovascular event rates without lipid or blood pressure lowering. In CANTOS, the magnitude of benefit of this cytokine-targeted approach to atherosclerosis treatment was associated to the magnitude of reduction of the central signaling cytokine IL-6 and the downstream clinical biomarker high-sensitivity CRP (C-reactive protein). By contrast, in the recent CIRT (Cardiovascular Inflammation Reduction Trial), low-dose methotrexate neither reduced IL-1ß, IL-6, or high-sensitivity CRP nor lowered cardiovascular event rates. Taken together, these 2 contemporary trials provide proof of principle that focused cytokine inhibition, not broad-spectrum anti-inflammatory therapy, is likely to be crucial for atheroprotection. This review provides an overview of cytokines in atherosclerosis, the potential benefits and risks associated with targeted anticytokine therapies, and a look to the future of clinical practices addressing residual inflammatory risk.

Modulation of Interleukin-1 and -18 Mediated Injury in Donation after Circulatory Death Mouse Hearts.

BACKGROUND: Donation after circulatory death donors (DCD) can expand the donor pool for heart transplantation, which primarily depends on brain death donors. Ischemia and reperfusion injury are inherent to the DCD process. We hypothesize that pharmacologic inhibition of interleukin-1 (IL-1) and/or IL-18 is protective to DCD hearts. MATERIALS AND METHODS: Following clinical protocol, in-situ ischemia time in control beating-heart donor (CBD) and DCD groups was less than 5 and 40 min, respectively. Wild type (WT) C57Bl6/j, IL-1 receptor type I knockout (IL-1RI-KO), and IL-18 KO mice were used. Hearts were reanimated for 90 min on a Langendorff system with Krebs-Henseleit buffer at 37°C, to assess physiologic parameters. Recombinant IL-1 receptor antagonist (IL-1Ra) and/or IL-18 binding protein (IL-18BP) were added to the Krebs-Henseleit buffer to inhibit IL-1 and/or the IL-18 signaling, respectively. RESULTS: Developed pressure and ± dP/dt were significantly impaired in the DCD-WT group compared to CBD-WT (P ≤ 0.05). Troponin release was higher in DCD-WT groups. Functional parameters were preserved, and troponin release was significantly less in the DCD knockout groups. Heart function was improved in DCD groups treated with IL-1Ra or IL-18BP compared to the DCD-WT group. CONCLUSIONS: Heart function was significantly impaired in the DCD-WT group compared to CBD-WT. Genetic deletion or pharmacologic blockade of IL-1 or IL-18 was protective to DCD hearts.

Effects of Interleukin-1ß Inhibition on Incident Hip and Knee Replacement : Exploratory Analyses From a Randomized, Double-Blind, Placebo-Controlled Trial.

BACKGROUND: Osteoarthritis is a common inflammatory disorder with no disease-modifying therapies. Whether inhibition of interleukin-1ß (IL-1ß) can reduce the consequences of large joint osteoarthritis is unclear. OBJECTIVE: To determine whether IL-1ß inhibition with canakinumab reduces incident total hip or knee replacement (THR/TKR). DESIGN: Exploratory analysis of a randomized trial. (ClinicalTrials.gov: NCT01327846). SETTING: 1091 clinical sites in 39 countries. PARTICIPANTS: 10 061 CANTOS (Canakinumab Anti-inflammatory Thrombosis Outcomes Study) participants. INTERVENTION: Random allocation to placebo or canakinumab (50, 150, or 300 mg) subcutaneously once every 3 months. MEASUREMENTS: The primary and secondary outcomes were time to first incident THR/TKR and time to first occurrence of an osteoarthritis-related adverse event (AE). Data were obtained through blinded ascertainment of trial clinical and safety databases. RESULTS: Median follow-up was 3.7 years. For the individual canakinumab dose groups, compared with placebo, hazard ratios (HRs) for incident THR/TKR during follow-up were 0.60 (95% CI, 0.38 to 0.95) for the 50-mg group, 0.53 (CI, 0.33 to 0.84) for the 150-mg group, and 0.60 (CI, 0.38 to 0.93) for the 300-mg group. Thus, in the pooled canakinumab groups, compared with the placebo group, incidence rates for THR/TKR were 0.31 and 0.54 events per 100 person-years (HR, 0.58 [CI, 0.42 to 0.80]; P = 0.001), respectively. The HR for the secondary end point of osteoarthritis-related AEs was 0.73 (CI, 0.61 to 0.87). Similar findings were observed in analyses restricted to participants with a history of osteoarthritis. LIMITATION: Because the parent trial was not designed to examine the efficacy of IL-1ß inhibitors in osteoarthritis, information on structural joint outcomes was not collected. CONCLUSION: Findings from this exploratory analysis of a randomized controlled trial support further investigation of IL-1ß inhibition for treatment of large joint osteoarthritis. PRIMARY FUNDING SOURCE: Novartis Pharmaceuticals.

Interleukin-18 and diabetic nephropathy: A review.

The inflammatory response has an important role in the pathophysiology of diabetic nephropathy that is contributed to by inflammatory mediators such as interleukin-1 (IL-1), IL-6, IL-18, tumor necrosis factor-α, and macrophage chemotactic protein-1; however, the role of IL-18 seems to be more specific than other cytokines in the inflammatory process. IL-18 is expressed in renal tissue and is upregulated by several stimuli including hyperglycemia. The expression/urinary level of IL-18 is positively correlated with the progression of diabetic nephropathy and the urinary albumin excretion rate. In this review, we have focused on the molecular pathways modulating the relationship between IL-18 and diabetic nephropathy.

Could the inhibition of IL-17 or IL-18 be a potential therapeutic opportunity for gastric cancer?

Chronic inflammation is recognized as a key tumor-promoting factor in a number of epithelial cancers, including gastric cancer (GC). The production of pro-inflammatory cytokines in the tumor microenvironment by both the innate and the adaptive immune response can activate signaling pathways that are associated with increased cell survival and proliferation of cancer cells. Among the cytokines that have most commonly been linked to inflammation-associated cancers, are the Th17 cell-associated cytokines IL-17A, IL-23, IL-22, and the IL-1 family members IL-1ß and IL-18. However, whether their contribution to inflammation-associated cancers is universal, or specific to individual types of cancers, remains to be elucidated. This review will explore our current understanding of the known roles of these cytokines in gastritis and discuss how their therapeutic inhibition may be useful for GC.

The protective effects of orexin a against high glucose-induced activation of NLRP3 inflammasome in human vascular endothelial cells.

Vascular disease is one of the most significant threats to the lives of patients suffering from diabetes, and chronic exposure of vascular endothelial cells to high glucose has been shown to significantly contribute to the process of endothelial cell dysfunction, one of the earliest events in diabetes-associated vascular disease. Nucleotide oligomerization domain (NOD)-like receptor pyrin domain-containing 3 (NLRP3) inflammasome plays a key role in initiating the inflammatory process by facilitating the production of interleukin-1ß (IL-1ß) and IL-18. ASC and caspase 1 are also implicated in NLRP3 inflammasome-mediated chronic inflammation. While under normal conditions, a balance exists between oxidants and antioxidants, exposure to high glucose significantly increases the production of ROS, which is enhanced by NOX4 expression. In the present study, we explored the role of orexin A, an endogenous peptide produced in the hypothalamus, in high glucose-induced activation of the NLRP3 inflammasome, oxidative stress, and expression of several key cytokines. Our findings demonstrate that orexin A exerts potent antioxidant effects in human aortic endothelial cells exposed to high glucose by inhibiting mitochondrial ROS and expression of NOX4 at both the mRNA and protein levels as revealed by MitoSOX staining, real-time PCR, and Western blot analysis. We also show that orexin A inhibits high glucose-induced expression of TxNIP, which is crucial to the activation of the NLRP3 inflammasome, as well as that of HMGB1. We confirmed via real-time PCR and Western blot analysis that orexin A suppressed the production of the inflammatory cytokines IL-1ß and IL-18. Additionally, through SIRT1 knockdown siRNA experimentation, we confirmed that SIRT1 knockdown abolishes the effects of orexin A described above, thereby indicating a critical role of SIRT in the capacity of orexin A to ameliorate high glucose-induced oxidative stress and activation of NLRP3 inflammasome.

Interleukin-18 in Health and Disease.

Interleukin (IL)-18 was originally discovered as a factor that enhanced IFN-γ production from anti-CD3-stimulated Th1 cells, especially in the presence of IL-12. Upon stimulation with Ag plus IL-12, naïve T cells develop into IL-18 receptor (IL-18R) expressing Th1 cells, which increase IFN-γ production in response to IL-18 stimulation. Therefore, IL-12 is a commitment factor that induces the development of Th1 cells. In contrast, IL-18 is a proinflammatory cytokine that facilitates type 1 responses. However, IL-18 without IL-12 but with IL-2, stimulates NK cells, CD4⁺ NKT cells, and established Th1 cells, to produce IL-3, IL-9, and IL-13. Furthermore, together with IL-3, IL-18 stimulates mast cells and basophils to produce IL-4, IL-13, and chemical mediators such as histamine. Therefore, IL-18 is a cytokine that stimulates various cell types and has pleiotropic functions. IL-18 is a member of the IL-1 family of cytokines. IL-18 demonstrates a unique function by binding to a specific receptor expressed on various types of cells. In this review article, we will focus on the unique features of IL-18 in health and disease in experimental animals and humans.

Efficacy and Pharmacology of the NLRP3 Inflammasome Inhibitor CP-456,773 (CRID3) in Murine Models of Dermal and Pulmonary Inflammation.

A critical component of innate immune response to infection and tissue damage is the NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome, and this pathway and its activation products have been implicated in the pathophysiology of a variety of diseases. NLRP3 inflammasome activation leads to the cleavage of pro-IL-1ß and pro-IL-18, as well as the subsequent release of biologically active IL-1ß, IL-18, and other soluble mediators of inflammation. In this study, we further define the pharmacology of the previously reported NLRP3 inflammasome-selective, IL-1ß processing inhibitor CP-456,773 (also known as MCC950), and we demonstrate its efficacy in two in vivo models of inflammation. Specifically, we show that in human and mouse innate immune cells CP-456,773 is an inhibitor of the cellular release of IL-1ß, IL-1α, and IL-18, that CP-456,773 prevents inflammasome activation induced by disease-relevant soluble and crystalline NLRP3 stimuli, and that CP-456,773 inhibits R848- and imiquimod-induced IL-1ß release. In mice, CP-456,773 demonstrates potent inhibition of the release of proinflammatory cytokines following acute i.p. challenge with LPS plus ATP in a manner that is proportional to the free/unbound concentrations of the drug, thereby establishing an in vivo pharmacokinetic/pharmacodynamic model for CP-456,773. Furthermore, CP-456,773 reduces ear swelling in an imiquimod cream-induced mouse model of skin inflammation, and it reduces airway inflammation in mice following acute challenge with house dust mite extract. These data implicate the NLRP3 inflammasome in the pathogenesis of dermal and airway inflammation, and they highlight the utility of CP-456,773 for interrogating the contribution of the NLRP3 inflammasome and its outputs in preclinical models of inflammation and disease.

In vitro evaluation of biomarkers of nephrotoxicity through gene expression using gentamicin.

Acute renal failure is one of the most frequent effects observed after taking medicine. Such situations have been tardily discovered, given that existing methods for assessing toxicity are not predictive. In this light, the present work evaluated the effects of gentamicin, a form of nephrotoxic drug, on HK-2 and HEK-293 cells. By using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and flow cytometry, both cells demonstrated that cytotoxicity occurs in a dose-dependent manner through the processes of apoptosis and cell necrosis. Gene expression analysis showed a relative increase of expression for genes related to cell processes and classic biomarkers, such as TP53, CASP3, CASP8, CASP9, ICAM-1, EXOC3, KIM-1, and CST3. A decrease in expression for genes BCL2L1 and EGF was observed. This study, therefore, indicates that, when the methods are used together, gene expression analysis is able to evaluate the nephrotoxic potential of a substance.

Influence of corticosteroid therapy on IL-18 and nitric oxide production during Behçet's disease.

BACKGROUND AND AIMS: Behçet's disease (BD) is a chronic multisystemic inflammatory disease with complex etiopathogenesis. Th1-proinflammatory cytokines seem to be involved in its pathogenesis. Our current study aims to evaluate interleukin-18 (IL-18) and nitric oxide (NO) involvement in the development of different clinical manifestations of BD as well as to investigate the corticosteroid therapy effect on this production in Algerian patients. METHODS: For this purpose, we evaluated in vivo and ex vivo IL-18, interferon-γ (IFN-γ) levels using ELISA and NO production by the Griess' method in naïve-active and corticosteroid-treated BD patients with different clinical manifestations. Additionally, we assessed CD40/CD40L expression by flow cytometrics assay in these groups of patients. RESULTS AND DISCUSSION: Our results indicate that IL-18 and nitrite levels were higher in naïve-active BD patients. Interestingly, this high production differed according to the clinical manifestations and was associated with an increased risk of mucocutaneous and vascular involvement. Concerning corticosteroid treated-active BD patients, no difference was observed in this production between each clinical subgroup. However, IFN-γ levels increased in all categories of active patients. Interestingly, corticosteroid therapy reduced significantly these inflammatory mediators regardless of the clinical manifestations studied. In addition, the CD40/CD40L expression differed according to the clinical presentations. CONCLUSION: Collectively, our results suggest that concomitant high production of IL-18 and NO in naïve-active BD patients is related to an increased risk of mucocutaneous lesions and vascular involvement. Moreover, the relationship between these two inflammatory markers could constitute a predictable tool of BD clinical presentations and an early factor of therapy efficiency.

TLR-Stimulated Neutrophils Instruct NK Cells To Trigger Dendritic Cell Maturation and Promote Adaptive T Cell Responses.

Polymorphonuclear neutrophils (PMNs) are innate effector cells with pivotal roles in pathogen recognition, phagocytosis, and eradication. However, their role in the development of subsequent immune responses is incompletely understood. This study aimed to identify mechanisms of relevance to the cross talk between human neutrophils and NK cells and its potential role in promoting adaptive immunity. TLR-stimulated PMNs were found to release soluble mediators to attract and activate NK cells in vitro. PMN-conditioned NK cells displayed enhanced cytotoxicity and cytokine production, and responded vigorously to ensuing stimulation with exogenous and endogenous IL-12. The neutrophil-induced activation of NK cells was prevented by caspase-1 inhibitors and by natural antagonists to IL-1 and IL-18, suggesting a role for the NOD-like receptor family pyrin domain containing-3 inflammasome. In addition, PMN-conditioned NK cells triggered the maturation of monocyte-derived dendritic cells, which promoted T cell proliferation and IFN-γ production. These data imply that neutrophils attract NK cells to sites of infection to convert these cells into an active state, which drives adaptive immune responses via maturation of dendritic cells. Our results add to a growing body of evidence that suggests a sophisticated role for neutrophils in orchestrating the immune response to pathogens.

YKL-40-Induced Inhibition of miR-590-3p Promotes Interleukin-18 Expression and Angiogenesis of Endothelial Progenitor Cells.

YKL-40, also known as human cartilage glycoprotein-39 or chitinase-3-like-1, is a pro-inflammatory protein that is highly expressed in rheumatoid arthritis (RA) patients. Angiogenesis is a critical step in the pathogenesis of RA, promoting the infiltration of inflammatory cells into joints and providing oxygen and nutrients to RA pannus. In this study, we examined the effects of YKL-40 in the production of the pro-inflammatory cytokine interleukin-18 (IL-18), and the stimulation of angiogenesis and accumulation of osteoblasts. We observed that YKL-40 induces IL-18 production in osteoblasts and thereby stimulates angiogenesis of endothelial progenitor cells (EPCs). We found that this process occurs through the suppression of miR-590-3p via the focal adhesion kinase (FAK)/PI3K/Akt signaling pathway. YKL-40 inhibition reduced angiogenesis in in vivo models of angiogenesis: the chick embryo chorioallantoic membrane (CAM) and Matrigel plug models. We report that YKL-40 stimulates IL-18 expression in osteoblasts and facilitates EPC angiogenesis.

IL-1ß and IL-18 inhibition of HIV-1 replication in Jurkat cells and PBMCs.

HIV-1 infection-induced apoptosis is able to ensure viral replication. The death of some CD4+ T cells residing in lymphoid tissues can be induced by HIV-1 infection through caspase-1 driven pyroptosis with release of cytokine of IL-1ß and IL-18. It is not well known whether IL-1ß and IL-18 affect HIV-1 replication in lymphocytic cells. Using susceptible lymphocytic cell line, Jurkat cells, and primary peripheral blood mononuclear cells (PBMCs), we studied the effects of IL-1ß and IL-18 on HIV-1 replication. We found that treatment with exogenous IL-1ß protein (rIL-1ß) and IL-18 protein (rIL-18), or expression of IL-1ß and IL-18 significantly reduced HIV-1 replication. HIV-1 infection enhanced caspase-3 expression and its activation, and had no effects on caspase-1 activity. Treatment with rIL-1ß and rIL-18 dramatically lowered caspase-3 activity. IL-1ß and IL-18 also played roles in diminishing reactivation of viral replication from latency in J1.1 cells. These results indicate that IL-1ß and IL-18 are able to inhibit HIV-1 replication, and their effects may be due to signaling through apoptosis involved in inactivation of caspase-3 activity.

The role of IL-18 in type 1 diabetic nephropathy: The problem and future treatment.

Diabetic vascular complication is a leading cause of diabetic nephropathy, a progressive increase in urinary albumin excretion coupled with elevated blood pressure leading to declined glomerular filtration and eventually end stage renal failure. There is growing evidence that activated inflammation is contributing factor to the pathogenesis of diabetic nephropathy. Meanwhile, IL-18, a member of the IL-1 family of inflammatory cytokines, is involved in the development and progression of diabetic nephropathy. However, the benefits derived from the current therapeutics for diabetic nephropathy strategies still provide imperfect protection against renal progression. This imperfection points to the need for newer therapeutic agents that have potential to affect primary mechanisms contributing to the pathogenesis of diabetic nephropathy. Therefore, the recognition of IL-18 as significant pathogenic mediators in diabetic nephropathy leaves open the possibility of new potential therapeutic targets.

Interleukin-18 enhances breast cancer cell migration via down-regulation of claudin-12 and induction of the p38 MAPK pathway.

Interleukin-18 (IL-18) was recently reported to have a pro-tumor effect in various cancers. Increased IL-18 levels in the serum of cancer patients correlated with malignancy, and IL-18 acts a crucial factor for cell migration in gastric cancer and melanoma. Claudins, which are the most important tight junction proteins, are also linked with cancer progression and metastasis. However, the relationship between claudins and IL-18 is not well-understood. Here, we show that the migratory ability of MCF-7 cells was reduced when endogenous IL-18 expression was inhibited with IL-18 siRNA. Moreover, exogenous IL-18 enhanced breast cancer cell migration and suppressed the expression of the tight junction proteins claudin-1, claudin-3, claudin-4, and claudin-12 in MCF-7 cells. Knockdown of claudin-3, claudin-4, and claudin-12, but not claudin-1, increased breast cancer migration with maximal effects observed in claudin-12 siRNA-transfected cells. To investigate whether the mitogen-activated protein kinase (MAPK) signaling pathway is involved in IL-18-induced cell migration and claudin-12 expression, cells were pretreated with SB203580 (an inhibitor of p38 MAPK) or PD98059 (an inhibitor of ERK1/2) prior to the addition of IL-18. Although pretreatment of MCF-7 cells with SB203580 blocked both the enhanced cell migration and the decreased claudin-12 expression, PD98059 only blocked cell migration and did not affect claudin-12 expression. In addition, exogenous IL-18 induced rapid phosphorylation of p38 MAPK. These results suggest that IL-18 is an important factor inducing breast cancer cell migration through down-regulation of claudin-12 and activation of the p38 MAPK pathway.

Activation of decidual invariant natural killer T cells promotes lipopolysaccharide-induced preterm birth.

Invariant natural killer T (iNKT) cells are crucial for host defense against a variety of microbial pathogens, but the underlying mechanisms of iNKT cells activation by microbes are not fully explained. In this study, we investigated the molecular mechanisms of iNKT cell activation in lipopolysaccharide (LPS)-stimulated preterm birth using an adoptive transfer system and diverse neutralizing antibodies (Abs) and inhibitors. We found that adoptive transfer of decidual iNKT cells to LPS-stimulated iNKT cell deficient Jα18(-/-) mice that lack invariant Vα14Jα281T cell receptor (TCR) expression significantly decreased the time to delivery and increased the percentage of decidual iNKT cells. Neutralizing Abs against Toll-like receptor 4 (TLR-4), CD1d, interleukin (IL)-12 and IL-18, and inhibitors blocking the activation of nuclear factor κB (NF-κB), mitogen-activated protein kinase (MAPK) p38 and extracellular signal-regulated kinase (ERK) significantly reduced in vivo percentages of decidual iNKT cells, their intracellular interferon (IFN)-γ production and surface CD69 expression. In vitro, in the presence of the same Abs and inhibitors used as in vivo, decidual iNKT cells co-cultured with LPS-pulsed dendritic cells (DCs) showed significantly decreased extracellular and intracellular IFN-γ secretion and surface CD69 expression. Our data demonstrate that the activation of decidual iNKT cells plays an important role in inflammation-induced preterm birth. Activation of decidual iNKT cells also requires TLR4-mediated NF-κB, MAPK p38 and ERK pathways, the proinflammatory cytokines IL-12 and IL-18, and endogenous glycolipid antigens presented by CD1d.

Simultaneous targeting of IL-1 and IL-18 is required for protection against inflammatory and septic shock.

RATIONALE: Sepsis is one of the leading causes of death around the world. The failure of clinical trials to treat sepsis demonstrates that the molecular mechanisms are multiple and are still insufficiently understood. OBJECTIVES: To clarify the long disputed hierarchical contribution of several central inflammatory mediators (IL-1ß, IL-18, caspase [CASP] 7, CASP1, and CASP11) in septic shock and to explore their therapeutic potential. METHODS: LPS- and tumor necrosis factor (TNF)-induced lethal shock, and cecal ligation and puncture (CLP) were performed in genetically or pharmacologically targeted mice. Body temperature and survival were monitored closely, and plasma was analyzed for several markers of cellular disintegration and inflammation. MEASUREMENTS AND MAIN RESULTS: Interestingly, deficiency of both IL-1ß and IL-18 additively prevented LPS-induced mortality. The detrimental role of IL-1ß and IL-18 was confirmed in mice subjected to a lethal dose of TNF, or to a lethal CLP procedure. Although their upstream activator, CASP1, and its amplifier, CASP11, are considered potential therapeutic targets because of their crucial involvement in endotoxin-induced toxicity, CASP11- or CASP1/11-deficient mice were not, or hardly, protected against a lethal TNF or CLP challenge. In line with our results obtained in genetically deficient mice, only the combined neutralization of IL-1 and IL-18, using the IL-1 receptor antagonist anakinra and anti-IL-18 antibodies, conferred complete protection against endotoxin-induced lethality. CONCLUSIONS: Our data point toward the therapeutic potential of neutralizing IL-1 and IL-18 simultaneously in sepsis, rather than inhibiting the upstream inflammatory caspases.

Interleukin-18 as a therapeutic target in acute myocardial infarction and heart failure.

Interleukin 18 (IL-18) is a proinflammatory cytokine in the IL-1 family that has been implicated in a number of disease states. In animal models of acute myocardial infarction (AMI), pressure overload, and LPS-induced dysfunction, IL-18 regulates cardiomyocyte hypertrophy and induces cardiac contractile dysfunction and extracellular matrix remodeling. In patients, high IL-18 levels correlate with increased risk of developing cardiovascular disease (CVD) and with a worse prognosis in patients with established CVD. Two strategies have been used to counter the effects of IL-18:IL-18 binding protein (IL-18BP), a naturally occurring protein, and a neutralizing IL-18 antibody. Recombinant human IL-18BP (r-hIL-18BP) has been investigated in animal studies and in phase I/II clinical trials for psoriasis and rheumatoid arthritis. A phase II clinical trial using a humanized monoclonal IL-18 antibody for type 2 diabetes is ongoing. Here we review the literature regarding the role of IL-18 in AMI and heart failure and the evidence and challenges of using IL-18BP and blocking IL-18 antibodies as a therapeutic strategy in patients with heart disease.