Fulminant Viral Hepatitis in Two Siblings with Inherited IL-10RB Deficiency.

Fulminant viral hepatitis (FVH) caused by hepatitis A virus (HAV) is a life-threatening disease that typically strikes otherwise healthy individuals. The only known genetic etiology of FVH is inherited IL-18BP deficiency, which unleashes IL-18-dependent lymphocyte cytotoxicity and IFN-γ production. We studied two siblings who died from a combination of early-onset inflammatory bowel disease (EOIBD) and FVH due to HAV. The sibling tested was homozygous for the W100G variant of IL10RB previously described in an unrelated patient with EOIBD. We show here that the out-of-frame IL10RB variants seen in other EOIBD patients disrupt cellular responses to IL-10, IL-22, IL-26, and IFN-λs in overexpression conditions and in homozygous cells. By contrast, the impact of in-frame disease-causing variants varies between cases. When overexpressed, the W100G variant impairs cellular responses to IL-10, but not to IL-22, IL-26, or IFN-λ1, whereas cells homozygous for W100G do not respond to IL-10, IL-22, IL-26, or IFN-λ1. As IL-10 is a potent antagonist of IFN-γ in phagocytes, these findings suggest that the molecular basis of FVH in patients with IL-18BP or IL-10RB deficiency may involve excessive IFN-γ activity during HAV infections of the liver. Inherited IL-10RB deficiency, and possibly inherited IL-10 and IL-10RA deficiencies, confer a predisposition to FVH, and patients with these deficiencies should be vaccinated against HAV and other liver-tropic viruses.

Production of recombinant human long-acting IL-18 binding protein: inhibitory effect on ulcerative colitis in mice.

Interleukin-18 binding protein (IL-18BP) is a natural IL-18 inhibitor in vivo, which can effectively neutralize IL-18 and inhibit the inflammatory signaling pathway induced by IL-18, thus playing an anti-inflammatory role. Traditional production methods primarily rely on eukaryotic animal cell expression systems, which often entail complex processes, lower yields, and increase production costs. In this study, we present a novel approach for expressing IL-18BP fusion protein using the Escherichia coli (E. coli) system. The N-terminal segment of IL-18BP was fused with the small ubiquitin-related modifier (SUMO) tag, enabling soluble expression, while the C-terminal segment was fused with the human IgG1 Fc fragment to prolong its in vivo lifespan. Through screening, we obtained a high-expression engineering strain from a single colony and developed optimized protocols for fermentation and purification of the recombinant SUMO-IL-18BP-Fc protein. The SUMO tag was subsequently cleaved using SUMO protease, and the purified recombinant human IL-18BP-Fc (rhIL-18BP-Fc) exhibited a purity exceeding 90% with a yield of 1 g per liter of bacterial solution. The biological activities and underlying mechanisms of rhIL-18BP-Fc were evaluated using cell lines and a mouse model. Our results demonstrated that rhIL-18BP-Fc effectively inhibited IL-18-stimulated IFN-γ production in KG-1a cells in vitro and ameliorated DSS-induced ulcerative colitis in mice. In conclusion, we successfully employed the SUMO fusion system to achieve high-level production, soluble expression, and prolonged activity of rhIL-18BP-Fc in E. coli. These findings lay the groundwork for future large-scale industrial production and pharmaceutical development of rhIL-18BP-Fc protein. KEY POINTS: • Effective expression, fermentation, and purification of bioactive rhIL-18BP-Fc protein in E. coli. • The rhIL-18BP-Fc protein has a great potential for the therapy of ulcerative colitis by inhibiting the expression of inflammatory factors.

Elevated serum free IL-18 in neuropsychiatric systemic lupus erythematosus patients with seizure disorders.

BACKGROUND: Since dysregulation of total Interleukin (IL)-18 and IL-18 binding protein (IL-18BP) may participate in systemic lupus erythematosus (SLE) and contribute to the occurrence of non-autoimmune epilepsy, the aim of the current work is to investigate whether the interaction between IL-18 and IL-18BP plays any role in neuropsychiatric systemic lupus erythematosus related seizures. METHODS: Data from 137 SLE patients and 30 healthy controls (HC) were consecutively collected from 2020 to 2021. Serum levels of total IL-18 and IL-18BP for all patients and HC were measured by ELISA test. Free IL-18 was calculated based on the law of mass action. RESULTS: Among the 137 SLE patients, 103 had active disease and were classified into NPSLE (n = 50) and Non-NPSLE (n = 53) groups. Among the NPSLE patients, 16 had seizure disorders. Serum free IL-18 levels were increased in NPSLE (277.6 [150.9-428.8]pg/mL) and were correlated with disease activity (r = 0.268, p = 0.002). Moreover, serum free IL-18 levels in NPSLE patients with seizure disorders (350.9 [237.9-455.9]pg/mL) were significantly higher than the levels in those with other neuropsychiatric symptoms (237.7 [124.6-428.8] pg/mL). CONCLUSIONS: The expression of free IL-18 was increased in neuropsychiatric systemic lupus erythematosus(NPSLE), especially in NPSLE related seizures. Also, serum levels of free IL-18 were significantly increased in active SLE patients. In this regard, free IL-18 may be involved in the pathogenesis of NPSLE related seizures and associated with disease activity.

IL-18 and IL-18 binding protein are related to disease severity and parasitemia during falciparum malaria.

BACKGROUND: Several inflammatory molecules participate in the immune response to malaria. Interleukin (IL)-18 is an inflammatory cytokine activated by NLRP3 inflammasomes. In clinical falciparum malaria, with and without HIV co-infection, data on IL-18 and in particular on its binding protein, IL-18bp, is scarce. METHODS: Clinical data and blood samples were collected from adults in Mozambique with P. falciparum infection, with (n = 70) and without (n = 61) HIV co-infection, from HIV-infected patients with similar symptoms without malaria (n = 58) and from healthy controls (n = 52). In vitro studies were performed in endothelial cells using hemozoin crystals. RESULTS: (i) IL-18 and IL-18bp were markedly up-regulated during falciparum malaria with particular high levels in malaria patients co-infected with HIV and severe malaria disease. (ii) In the malaria group as a whole, both IL-18 and IL-18bp were positively correlated with disease severity, parasitemia, and endothelial cell activation as assessed by vWF in plasma. (iii) Whereas there was no change in IL-18 levels in malaria patients co-infected with HIV during follow-up, the patients with malaria only had slightly increased IL-18 levels. Further, the IL-18pb levels declined and thereby contributed to an increase in IL-18/IL-18bp ratio in all subgroups of malaria patients. (iv) IL-27, previously shown to be up-regulated in this malaria cohort, markedly induced a release of IL-18bp from endothelial cells in vitro, and notably, this presumably anti-inflammatory effect was counteracted by hemozoin. CONCLUSIONS: Our findings suggest that the IL-18 system could be an important mediator in the immune pathogenesis during falciparum malaria, potentially also representing a target for therapy.

Emerging Roles for Interleukin-18 in the Gastrointestinal Tumor Microenvironment.

Interleukin (IL)-18, a member of the IL-1 family of cytokines, has emerged as a key regulator of mucosal homeostasis within the gastrointestinal tract. Like other members of this family, IL-18 is secreted as an inactive protein and is processed into its active form by caspase-1, although other contributors to precursor processing are emerging.Numerous studies have evaluated the role of IL-18 within the gastrointestinal tract using genetic or complementary pharmacological tools and have revealed multiple roles in tumorigenesis. Most striking among these are the divergent roles for IL-18 in colon and gastric cancers. Here, we review our current understanding of IL-18 biology and how this applies to colorectal and gastric cancers.

Role of IL-18 in atopic asthma is determined by balance of IL-18/IL-18BP/IL-18R.

It is recognized that IL-18 is related to development of asthma, but role of IL-18 in asthma remains controversial and confusing. This is largely due to lack of information on expression of IL-18 binding protein (BP) and IL-18 receptor (R) in asthma. In this study, we found that plasma levels of IL-18 and IL-18BP were elevated in asthma. The ratio between plasma concentrations of IL-18 and IL-18BP was 1:12.8 in asthma patients. We demonstrated that 13-fold more monocytes, 17.5-fold more neutrophils and 4.1-fold more B cells express IL-18BP than IL-18 in asthmatic blood, suggesting that there is excessive amount of IL-18BP to abolish actions of IL-18 in asthma. We also discovered that more IL-18R+ monocytes, neutrophils and B cells are located in asthmatic blood. Once injected, IL-18 eliminated IL-18R+ monocytes in blood, but up-regulated expression of IL-18R in lung macrophages of OVA-sensitized mice. Our data clearly indicate that the role of IL-18 in asthma is very likely to be determined by balance of IL-18/IL-18BP/IL-18R expression in inflammatory cells. Therefore, IL-18R blocking or IL-18BP activity enhancing therapies may be useful for treatment of asthma.

Differential synthesis and release of IL-18 and IL-18 Binding Protein from human platelets and their implications for HIV infection.

IL-18 is a pro-inflammatory cytokine belonging to the IL-1 family and is produced in the body from macrophages, epithelial and dendritic cells, keratinocytes, adrenal cortex etc. The cytokine is produced as an inactive precursor that is cleaved inside cells into its mature form by activated caspase 1, which exists as an inactive precursor in human cells and requires assembly of an inflammasomes for its activation. We show here for the first time that human platelets contain transcripts for the IL-18 gene. They synthesize the cytokine de novo, process and release it upon activation. The activation also results in the assembly of an inflammasome and activation of caspase-1. Platelets also contain the IL-18 antagonist, the IL-18-Binding Protein (IL-18BP); however, it is not synthesized in them de novo, is present in pre-made form and is released irrespective of platelet activation. IL-18 and IL-18BP co-localize to α granules inside platelets and are secreted out with different kinetics. Platelet activation contributes to plasma concentrations in healthy individuals, as their plasma samples contain abundant IL-18, while their platelet-poor plasma samples contain very little amounts of the cytokine. The plasma and PPP samples from these donors, however, contain comparable amounts of IL-18BP. Unlike healthy individuals, the platelet-poor plasma from HIV-infected individuals contains significant amounts of IL-18. Our findings have important implications for viral infections and other human diseases that are accompanied by platelet activation.

A potentially protective role of IL-18 Binding Protein in HIV-infected Long-Term Non-Progressors.

An imbalance between IL-18 and its antagonist, IL-18 Binding Protein, occurs in the circulation of HIV-infected individuals. We show here for the first time that HIV-infected Long Term Non-Progressors (LTNPs) do not develop this imbalance, and maintain normal levels of IL-18BP in the circulation. Their circulating levels of the antagonist correlate negatively with viral loads and show a positive trend with CD4+ T cells counts. The maintenance of normal production of IL-18BP may contribute, at least in part, to the ability of LTNPs to delay AIDS progression.

Blockade of IL-18 signaling diminished neuropathic pain and enhanced the efficacy of morphine and buprenorphine.

Currently, the low efficacy of antinociceptive drugs for the treatment of neuropathic pain is a major therapeutic problem. Here, we show the potential role of interleukin (IL)-18 signaling in this phenomenon. IL-18 is an important molecule that performs various crucial functions, including the alteration of nociceptive transmission in response to neuropathic pain. We have studied the changes in the mRNA and protein levels (qRT-PCR and Western blot analysis, respectively) of IL-18, IL-18-binding protein (IL-18BP) and the IL-18 receptor (IL-18R) over time in rats following chronic constriction injury (CCI) of the sciatic nerve. Our study demonstrated that the spinal levels of IL-18BP were slightly downregulated at days 7 and 14 in the rats subjected to CCI. In contrast, the IL-18 and IL-18R mRNA expression and protein levels were elevated in the ipsilateral spinal cord on days 2, 7 and 14. Moreover, in rats exposed to a single intrathecal administration of IL-18BP (50 and 100 ng) 7 or 14 days following CCI, symptoms of neuropathic pain were attenuated, and the analgesia pursuant to morphine and buprenorphine (0.5 and 2.5 µg) was enhanced. In summary, the restoration of the analgesic activity of morphine and buprenorphine via the blockade of IL-18 signaling suggests that increased IL-18 pathway may account for the decreased analgesic efficacy of opioids for neuropathic pain.

Elevated serum levels of free interleukin-18 in adult-onset Still's disease.

OBJECTIVE: IL-18 is a pro-inflammatory cytokine of the IL-1 family that is naturally inhibited by IL-18 binding protein (IL-18BP). High levels of IL-18 have been described in the serum of adult-onset Still's disease (AOSD) patients, but only total IL-18 levels (including inactive IL-18 bound to IL-18BP) have been measured. With a specific immunoassay, we aimed to measure free IL-18 serum levels in AOSD patients and other rheumatic diseases. METHODS: An ELISA was developed to measure free IL-18. Its sensitivity and specificity were tested by spiking recombinant IL-18 or IL-18BP in serum and PBS supplemented with 5% BSA. The binding affinity of IL-18 to IL-18BP was calculated by titration experiments using the ELISA and by Biacore analysis. Sera of 37 AOSD patients and 138 controls (40 healthy controls, 30 RA, 29 SLE, 21 AS and 18 PsA) were assayed for free IL-18, IL-18BP, total IL-18 and other cytokines. Correlations were performed between free IL-18 and markers of disease activity in AOSD patients. RESULTS: Free IL-18 serum levels were significantly higher in AOSD patients (median 8.89 pg/ml) than in healthy and disease controls (1.37 pg/ml; P < 0.01). Free IL-18 serum levels correlated with AOSD activity. The affinity of IL-18 to IL-18BP was found to be much higher than previously described, with a dissociation constant ranging from 30 to 50 pM. CONCLUSION: Free IL-18 levels are specifically elevated in AOSD compared with other inflammatory diseases, suggesting that IL-18 represents a potential target for the treatment of AOSD.

Imbalanced production of IL-18 and its antagonist in human diseases, and its implications for HIV-1 infection.

IL-18 is a pleiotropic and multifunctional cytokine that belongs to the IL-1 family. It is produced as a biologically inactive precursor, which is cleaved into its active mature form mainly by caspase-1. The caspase becomes active from its inactive precursor (procaspase-1) upon assembly of an inflammasome. Because of IL-18's potential pro-inflammatory and tissue destructive effects, its biological activities are tightly controlled in the body by its naturally occurring antagonist called IL-18BP. The antagonist is produced in the body both constitutively and in response to an increased production of IL-18 as a negative feedback mechanism. Under physiological conditions, most of IL-18 in the circulation is bound with IL-18BP and is inactive. However, an imbalance in the production of IL-18 and its antagonist (an increase in the production of IL-18 with a decrease, no increase or an insufficient increase in the production of IL-18BP) has been described in many chronic inflammatory diseases in humans. The imbalance results in an increase in the concentrations of free IL-18 (unbound with its antagonist) resulting in increased biological activities of the cytokine that contribute towards pathogenesis of the disease. In this article, we provide an overview of the current biology of IL-18 and its antagonist, discuss how the imbalance occurs in HIV infections and how it contributes towards development of AIDS and other non-AIDS-associated clinical conditions occurring in HIV-infected individuals undergoing combination anti-retroviral therapy (cART). Finally, we discuss challenges facing immunotherapeutic strategies aimed at restoring balance between IL-18 and its antagonist in these patients.

The effects of IL-18BP on mRNA expression of inflammatory cytokines and apoptotic genes in renal injury induced by infrarenal aortic occlusion.

BACKGROUND: Renal injury is an important complication of infrarenal aortic occlusion (IAO), which is mainly encountered during the postoperative period. Aortic clamping procedure may lead to turbulent blood flow and eventually vasoconstriction at renal arterial level of the abdominal aorta. IL-18BP has well-known antioxidant and anti-inflammatory properties. In this study, we aimed to determine whether IL-18BP has anti-inflammatory, antiapoptotic, antioxidant, and protective effects on acute kidney damage induced by IAO rat model. MATERIALS AND METHODS: A total of 30 adult male Wistar-Albino rats were equally and randomly separated to three groups as follows: SHAM laparotomy, ischemia-reperfusion (IR), and IR + IL-18BP. We applied 30-min IAO and 2-h reperfusion. Inflammatory cytokine levels (TNF-α, IL-1ß, IL-18, IL-6, and IFN-γ) and oxidative stress parameters (TAS, TOS, and OSI) were measured. In addition to this, urea and creatinine levels, histopathology of kidney, mRNA expression levels of inflammatory cytokines, and apoptotic genes were investigated. RESULTS: Urea and creatinine, tissue and serum levels of TNF-α, IL-6, IL-18, IFN-γ, and TOS, and oxidative stress index (OSI) were found significantly lower in IR + IL-18BP group, when compared to the IR group. Moreover, mRNA expression levels of inflammatory cytokines and apoptotic genes were prominently depressed in IR + IL-18BP pre-treatment group in histopathologic examination, there was a significant difference between the IR and other three groups (P < 0.001). These improvements were demonstrated with a total score of histopathologic damage. In our previous studies, we have demonstrated that IL-18BP has antioxidant, inflammatory, and protective effects on liver and spinal cord IR injury. Data established from the present study suggest that IL-18BP may exert anti-inflammatory, antiapoptotic, antioxidant, and protective effects on IAO-induced acute kidney injury in rats, and this would be the first study to be conducted in this field. CONCLUSIONS: Data established from the present study suggest that IL-18BP may exert anti-inflammatory, antiapoptotic, antioxidant, and protective effects on IAO-induced acute kidney injury in rats.

Increased IL18 mRNA levels in peripheral artery disease and its association with triglyceride and LDL cholesterol levels: a pilot study.

Peripheral artery disease (PAD) typically refers to lower limb vessel ischemia caused by atherosclerotic stenosis of lower extremity arteries. IL18 is a pleiotropic pro-inflammatory cytokine reported to function as an inflammatory biomarker in cardiovascular diseases. IL18 activity is balanced by high-affinity naturally occurring IL18-binding protein (IL18BP). This study aimed to determine whether IL18, IL18 BP mRNA levels and -137 G/C (rs187238) polymorphism, which was previously associated with IL18 gene transcriptional activity, were associated with PAD etiology. IL18, IL18BP mRNA levels from peripheral blood mononuclear cells and -137 G/C (rs187238) polymorphism were determined by quantitative real-time polymerase chain reaction (qRT-PCR) and RT-PCR, respectively, in 55 PAD patients (26 aorta-iliac, 29 femoro-popliteal) and 61 disease-free controls. IL18 mRNA levels were increased in PAD patients compared with healthy controls (p = 0.09); however, did not reach a statistical significant level, also did not significantly differ between aorta-iliac and femoro-popliteal occlusive PAD subgroups (p = 0.285). However, IL18BP mRNA levels were significantly lower in PAD group compared with controls (p < 0.001). Genotype frequencies of rs187238 polymorphism did not significantly differ between PAD patients and controls (p = 0.385). IL18 mRNA levels were significantly correlated with triglycerides and LDL cholesterol levels in PAD patients (p = 0.003, p = 0.014, respectively). HDL cholesterol levels were negatively correlated with IL18 mRNA levels in controls (p = 0.05). This report is a preliminary study to show an association between IL18, IL18BP mRNA levels and PAD and suggests that the IL18 gene may have a significant relationship with triglyceride and LDL cholesterol levels in PAD patients.

Systemic toll-like receptor and interleukin-18 pathway activation in patients with acute ST elevation myocardial infarction.

Acute myocardial infarction (AMI) is accompanied by increased expression of Toll like receptors (TLR)-2 and TLR4 on circulating monocytes. In animal models, blocking TLR2/4 signaling reduces inflammatory cell influx and infarct size. The clinical consequences of TLR activation during AMI in humans are unknown, including its role in long-term cardiac functional outcome Therefore, we analyzed gene expression in whole blood samples from 28 patients with an acute ST elevation myocardial infarction (STEMI), enrolled in the EXenatide trial for AMI patients (EXAMI), both at admission and after 4-month follow-up, by whole genome expression profiling and real-time PCR. Cardiac function was determined by cardiac magnetic resonance (CMR) imaging at baseline and after 4-month follow-up. TLR pathway activation was shown by increased expression of TLR4 and its downstream genes, including IL-18R1, IL-18R2, IL-8, MMP9, HIF1A, and NFKBIA. In contrast, expression of the classical TLR-induced genes, TNF, was reduced. Bioinformatics analysis and in vitro experiments explained this noncanonical TLR response by identification of a pivotal role for HIF-1α. The extent of TLR activation and IL-18R1/2 expression in circulating cells preceded massive troponin-T release and correlated with the CMR-measured ischemic area (R=0.48, p=0.01). In conclusion, we identified a novel HIF-1-dependent noncanonical TLR activation pathway in circulating leukocytes leading to enhanced IL-18R expression which correlated with the magnitude of the ischemic area. This knowledge may contribute to our mechanistic understanding of the involvement of the innate immune system during STEMI and may yield diagnostic and prognostic value for patients with myocardial infarction.

Activation of the Interleukin-18 Signaling Pathway via Direct Receptor Dimerization in the Absence of Interleukin-18.

Interleukin 18 (IL-18) is a key cytokine involved in the activation of T and NK cells, which are major effector cells in tumor killing. However, recombinant IL-18 showed limited efficacy in clinical trials. A recent study showed the lack of efficacy was largely due to the existence of IL-18BP, a soluble decoy receptor for IL-18. It was shown that engineered IL-18 variants that maintained pathway activation, but avoided IL-18BP binding, could exert potent antitumor effects. In this study, we demonstrated an alternative strategy to activate IL-18 signaling through direct receptor dimerization. These results provide evidences that the IL-18 pathway can be activated by directly bridging the receptors and, therefore, bypassing the IL-18BP-mediated inhibition.

Blood Interleukin-18 (IL-18) and IL-18 Binding Protein (IL-18BP) Levels Following Midline Laparotomy: A Prospective Randomized Study of Patients With Benign Disease and Patients With Cancer.

BACKGROUND/AIM: The acute phase immune response (APR) in midline laparotomy (MLa) patients following surgery has been rarely studied, with no studies assessing the association of blood IL-18 (interleukin-18) and IL-18BP (IL-18 binding protein) values with the numeric rating scale (NRS) pain score following MLa. PATIENTS AND METHODS: Blood levels of seven cytokines (CYT) (IL-18, IL-18BP, IL-1ra, IL-6, IL-8, IL-10, IL-1ß) and high-sensitivity C-reactive protein (hs-CRP) were measured at three time points; before operation (PRE), immediately after operation (POP1), and 24 h after operation (POP2) in 56 patients with MLa. The satisfaction of the patients at 24 h following MLa (SFS24; 0=fully unsatisfied; 10=fully satisfied) was recorded on a 11-point numeric rating scale. RESULTS: In all patients, the IL-18 and IL-18BP blood levels decreased at POP1 and the drop between the preoperative and POP1 levels in the IL-18 and IL-18BP was highly significant (p<0.001). However, the median IL-18 and IL-18BP blood levels increased significantly at POP2 (p<0.001) with the linear mixed-effect model (LME) showing a statistically significant time effect (p<0.001). The hs-CRP blood levels increased significantly at POP2 with the LME model showing a statistically significant time effect. The preoperative and POP2 IL-18 values were clearly higher in patients with cancer versus benign disease (177/182 vs. 135/126, p=0.039/p=0.013, respectively). Interestingly, in all patients of the study, the median IL-18 versus IL-18BP blood levels correlated at POP1 (r=0.315, p=0.036). CONCLUSION: A noteworthy discovery of this study is the correlation of IL-18BP with SFS24 (r=0.361, p=0.05), proposing that APR and quality of life are associated in MLa patients.

Interleukin-18 Binding Protein (IL-18BP): A Long Journey From Discovery to Clinical Application.

IL-18 binding protein (IL-18BP) was originally discovered in 1999 while attempting to identify an IL-18 receptor ligand binding chain (also known as IL-18Rα) by subjecting concentrated human urine to an IL-18 ligand affinity column. The IL-18 ligand chromatography purified molecule was analyzed by protein microsequencing. The result revealed a novel 40 amino acid polypeptide. To isolate the complete open reading frame (ORF), various human and mouse cDNA libraries were screened using cDNA probe derived from the novel IL-18 affinity column bound molecule. The identified entire ORF gene was thought to be an IL-18Rα gene. However, IL-18BP has been proven to be a unique soluble antagonist that shares homology with a variety of viral proteins that are distinct from the IL-18Rα and IL-18Rß chains. The IL-18BP cDNA was used to generate recombinant IL-18BP (rIL-18BP), which was indispensable for characterizing the role of IL-18BP in vitro and in vivo. Mammalian cell lines were used to produce rIL-18BP due to its glycosylation-dependent activity of IL-18BP (approximately 20 kDa). Various forms of rIL-18BP, intact, C-terminal his-tag, and Fc fusion proteins were produced for in vitro and in vivo experiments. Data showed potent neutralization of IL-18 activity, which seems promising for clinical application in immune diseases involving IL-18. However, it was a long journey from discovery to clinical use although there have been various clinical trials since IL-18BP was discovered in 1999. This review primarily covers the discovery of IL-18BP along with how basic research influences the clinical development of IL-18BP.

A Possible Role of Interleukin-18 Binding Protein in Immune Regulation of Postoperative Pain: A Prospective Randomized Clinical Trial.

BACKGROUND/AIM: A possible role of interleukin-18 binding protein (IL-18BP) in immune regulation of pain and analgesics following surgery is rarely studied. The aim of this study was to investigate serum IL-18BP values in a cohort of laparoscopic cholecystectomy (LC) and minilaparotomy cholecystectomy (MC) patients and to establish their relationship with other cytokines and number of analgesic doses (NAD) of LC and MC patients postoperatively. PATIENTS AND METHODS: Blood levels of IL-18BP, six other interleukins (IL-18, IL-1ra, IL-6, IL-10, IL-1ß, and IL-8) and high-sensitivity C-reactive protein were measured before operation (PRE), immediately after operation (POP1), and six hours after operation (POP2) in 114 patients with cholelithiasis. RESULTS: Following surgery, the mean serum IL-18BP values correlated significantly to numeric rating scale (NRS) pain scores at 24 hours (r=0.194, p=0.009). In addition, the mean serum IL-18BP values correlated significantly to NAD (r=0.254, p<0.001). CONCLUSION: IL-18BP, a soluble antagonist of IL-18, correlates to NRS and NAD in LC and MC patients, which may support a possible role of IL-18BP in immune regulation of postoperative pain.

A natural goldmine of binding proteins and soluble receptors simplified their translation to blockbuster drugs, all in one decade.

Human urinary proteins are a goldmine of natural proteins a feature that simplifies their translation to biologics. Combining this goldmine together with the ligand-affinity-chromatography (LAC) purification method, proved a winning formula in their isolation. LAC specificity, efficiency, simplicity and inherent indispensability in the search for predictable and unpredictable proteins, is superior to other separation techniques. Unlimited amounts of recombinant cytokines and monoclonal antibodies (mAb) accelerated the "triumph". My approach concluded 35 years of worldwide pursuit for Type I IFN receptor (IFNAR2) and advanced the understanding of the signal transduction of this Type of IFN. TNF, IFNγ and IL-6 as baits enabled the isolation of their corresponding soluble receptors and N-terminal amino acid sequence of the isolated proteins facilitated the cloning of their cell surface counterparts. IL-18, IL-32, and heparanase as the baits yielded the corresponding unpredictable proteins: the antidote IL-18 Binding Protein (IL-18BP), the enzyme Proteinase 3 (PR3) and the hormone Resistin. IFNß proved beneficial in Multiple Sclerosis and is a blockbuster drug, Rebif®. TNF mAbs translated into Remicade® to treat Crohn's disease. Enbrel® based on TBPII is for Rheumatoid Arthritis. Both are blockbusters. Tadekinig alfa™, a recombinant IL-18BP, is in phase III clinical study for inflammatory and autoimmune diseases. Seven years of continuous compassionate use of Tadekinig alfa™ in children born with mutations (NLRC4, XIAP) proved life-saving and is an example of tailored made medicine. IL-18 is a checkpoint biomarker in cancer and IL-18BP is planned recently to target cytokine storms resulting from CAR-T treatment and in COVID 19.

Detection of Free Bioactive IL-18 and IL-18BP in Inflammatory Disorders.

The interleukin (IL)-18 cytokine plays an important driver role in a range of autoimmune and inflammatory diseases, as well as cancer. IL-18 is a potent inducer of interferon gamma (IFN-γ), and the bioactivity of IL-18 is regulated by its natural soluble inhibitor, IL-18-binding protein (IL-18BP), which is present at high concentrations in the circulation. Many cell types have been described to secrete IL-18BP, constitutively or under the influence of IFN-γ, thus generating a negative feedback loop for IL-18. Therefore, solely measuring total IL-18 protein levels does not allow to evaluate its biological activity, especially in the context of systemic inflammatory diseases or other circumstances where IL-18BP is present (e.g., samples containing plasma, cells constitutively expressing IL-18BP). Considering there is a critical need to accurately measure the protein levels of both mature, biologically active IL-18 and IL-18BP as biomarkers of disease activity in patients and also stratification for potential anti-IL-18 therapy, in this chapter we provide the latest techniques to measure mature, free, and bioactive IL-18 and IL-18BP in different samples.