IL-18 mediates sickle cell cardiomyopathy and ventricular arrhythmias

Interleukin‑18 binding protein: Biological properties and roles in human and animal immune regulation (Review)

IL-18 binding protein (IL-18BP) is a natural regulatory molecule of the proinflammatory cytokine IL-18. It can regulate activity of IL-18 by high affinity binding. The present review aimed to highlight developments, characteristics and functions of IL-18BP. IL-18BP serves biological and anti-pathological roles in treating disease. In humans, it modulates progression of a number of chronic diseases, such as adult-onset Still's disease. The present review summarizes molecular structure, role of IL-18BP in disease and interaction with other proteins in important pathological processes.

Altered ventricular longitudinal strain in children with sickle cell disease: Role of TGF-β and IL-18

BACKGROUND

Cardiovascular involvement in sickle cell disease (SCD) has a great impact on patients' morbidity and mortality. Recently, interleukin-18 (IL-18) and transforming growth factor beta (TGF-β) were suggested as potential biomarkers for sickle cell cardiomyopathy. Global longitudinal strain (GLS) is a reliable early parameter for estimation of deformed myocardium. This study evaluated the role of TGF-β and IL-18 as risk indicators of altered strain in patients with SCD.

METHODS

Forty children with SCD (age >5 years) and 40 healthy children as controls, matched in age and sex, were enrolled in the study. All participants were subjected to clinical examination, complete blood count, serum ferritin, TGF-β, IL-18, and assessment of cardiac function by echocardiography.

RESULTS

TGF-β, IL-18, and lactic acid dehydrogenase (LDH) were significantly higher among cases (mean age: 10.6 ± 3.5 years) when compared to controls (p < .001), at cutoff values 41.7 ng/mL, 128.9 pg/mL, and 340 unit, respectively. The LS of free wall of RV (FW-RV) was significantly lower among cases when compared to controls (-23.55% ± 5.55% vs. -28.73% ± 2.43%, p < .001). Free wall longitudinal strain of the right ventricle (FWLS-RV) was significantly correlated to IL-18 and LDH (p < .001), while GLS-RV was significantly correlated to TGF-β. The GLS-LV was correlated to frequency of vaso-occlusive crises (VOCs) per year (p < .001). Diastolic function, E/A of LV, and RV were negatively correlated to the hemoglobin and serum ferritin levels.

CONCLUSIONS

The TGF-β, IL-18, and LDH along with frequent VOCs are correlated to altered LS, especially the right ventricle, and could serve as risk indicators for subclinical cardiomyopathy in children with SCD.

Empagliflozin alleviates the development of autoimmune myocarditis via inhibiting NF-κB-dependent cardiomyocyte pyroptosis

Autoimmune myocarditis, which falls within the broad spectrum of myocarditis, is characterized by an excessive inflammatory response in the heart, and can progress into dilated cardiomyopathy and irreversible heart failure in all possibility. However, effective clinical therapeutics are limited due to its complex inflammatory reactions. Empagliflozin (EMPA) has been previously demonstrated to possess anti-inflammatory properties. This study aimed to determine the improvement effects of EMPA on cardiac dysfunction under the condition of autoimmune myocarditis, and to further investigate the potential mechanisms. In vivo, all male Balb/c mice were randomly divided into four groups: control, experimental autoimmune myocarditis (EAM), EAM+EMPA and EMPA. In vitro, the effects of EMPA on IL-18-stimulated H9C2 cells were explored and the underlying molecular mechanisms were further determined. EMPA treatment significantly inhibited the development of autoimmune myocarditis, and mice treated with EMPA exhibited improved cardiac function compared with that in the EAM group, potentially through modulating pyroptosis of myocardium. Specifically, the NF-κB pathway was activated in the hearts of the EAM mice, which further activated NLRP3 inflammasome-dependent pyroptosis. EMPA treatment significantly inhibited such activation, thus alleviating inflammatory reactions in the context of EAM. Moreover, in vitro, we also observed that EMPA significantly inhibited pyroptosis of IL-18-stimulated H9C2 cells, and reduced nuclear translocation of NF-κB and degradation of activated IκBα. This work provides the first direct evidence that EMPA can inhibit myocardial inflammation and improve cardiac function in EAM mice, partly attributed to the drug-induced suppression of cardiomyocyte pyroptosis via disrupting the NF-κB pathway.

Mouse models of sickle cell disease: Imperfect and yet very informative

The root cause of sickle cell disease (SCD) has been known for nearly a century, however, few therapies to treat the disease are available. Over several decades of work, with advances in gene editing technology and after several iterations of mice with differing genotype/phenotype relationships, researchers have developed humanized SCD mouse models. However, while a large body of preclinical studies has led to huge gains in basic science knowledge about SCD in mice, this knowledge has not led to the development of effective therapies to treat SCD-related complications in humans, thus leading to frustration with the paucity of translational progress in the SCD field. The use of mouse models to study human diseases is based on the genetic and phenotypic similarities between mouse and humans (face validity). The Berkeley and Townes SCD mice express only human globin chains and no mouse hemoglobin. With this genetic composition, these models present many phenotypic similarities, but also significant discrepancies that should be considered when interpreting preclinical studies results. Reviewing genetic and phenotypic similarities and discrepancies and examining studies that have translated to humans and those that have not, offer a better perspective of construct, face, and predictive validities of humanized SCD mouse models.

Determinants of ventricular arrhythmias in sickle cell anemia: toward better prevention of sudden cardiac death

Sudden death is 1 of the leading causes of death in adults with sickle cell anemia (SCA) but its etiology remains mostly unknown. Ventricular arrhythmia (VA) carries an increased risk of sudden death; however, its prevalence and determinants in SCA are poorly studied. This study aimed to identify the prevalence and predictors of VA in patients with SCA. From 2019 to 2022, 100 patients with SCA were referred to the physiology department to specifically analyze cardiac function and prospectively included in the DREPACOEUR registry. They underwent a 24-hour electrocardiogram monitoring (24h-Holter), transthoracic echocardiography, and laboratory tests on the same day. The primary end point was the occurrence of VA, defined as sustained or nonsustained ventricular tachycardia (VT), >500 premature ventricular contractions (PVCs) on 24h-Holter, or a recent history of VT ablation. The mean patient age was 46 ± 13 years, and 48% of the patients were male. Overall, VA was observed in 22 (22%) patients. Male sex (81% vs 34%; P = .02), impaired global longitudinal strain (GLS): -16% ± 1.9% vs -18.3% ± 2.7%; P = .02), and decreased platelet count (226 ± 96 giga per liter [G/L] vs 316 ± 130 G/L) were independently associated with VA. GLS correlated with PVC load every 24 hours (r = 0.39; P < .001) and a cutoff of -17.5% could predict VA with a sensitivity of 82% and a specificity of 63%. VAs are common in patients with SCA, especially in men. This pilot study uncovered GLS as a valuable parameter for improving rhythmic risk stratification.

Pathophysiological characterization of the Townes mouse model for sickle cell disease

A deeper pathophysiologic understanding of available mouse models of sickle cell disease (SCD), such as the Townes model, will help improve preclinical studies. We evaluated groups of Townes mice expressing either normal adult human hemoglobin (HbA), sickle cell trait (HbAS), or SCD (HbS), comparing younger versus older adults, and females versus males. We obtained hematologic parameters in steady-state and hypoxic conditions and evaluated metabolic markers and cytokines from serum. Kidney function was evaluated by measuring the urine protein/creatinine ratio and urine osmolality. In vivo studies included von Frey assay, non-invasive plethysmography, and echocardiography. Histopathological evaluations were performed in lung, liver, spleen, and kidney tissues. HbS mice displayed elevated hemolysis markers and white blood cell counts, with some increases more pronounced in older adults. After extended in vivo hypoxia, hemoglobin, platelet counts, and white blood cell counts decreased significantly in HbS mice, whereas they remained stable in HbA mice. Cytokine analyses showed increased TNF-alpha in HbS mice. Kidney function assays revealed worsened kidney function in HbS mice. The von Frey assay showed a lower threshold to response in the HbS mice than controls, with more noticeable differences in males. Echocardiography in HbS mice suggested left ventricular hypertrophy and dilatation. Plethysmography suggested obstructive lung disease and inflammatory changes in HbS mice. Histopathological studies showed vascular congestion, increased iron deposition, and disruption of normal tissue architecture in HbS mice. These data correlate with clinical manifestations in SCD patients and highlight analyses and groups to be included in preclinical therapeutic studies.

SARS-CoV-2 spike protein induces IL-18-mediated cardiopulmonary inflammation via reduced mitophagy

Cardiopulmonary complications are major drivers of mortality caused by the SARS-CoV-2 virus. Interleukin-18, an inflammasome-induced cytokine, has emerged as a novel mediator of cardiopulmonary pathologies but its regulation via SARS-CoV-2 signaling remains unknown. Based on a screening panel, IL-18 was identified amongst 19 cytokines to stratify mortality and hospitalization burden in patients hospitalized with COVID-19. Supporting clinical data, administration of SARS-CoV-2 Spike 1 (S1) glycoprotein or receptor-binding domain (RBD) proteins into human angiotensin-converting enzyme 2 (hACE2) transgenic mice induced cardiac fibrosis and dysfunction associated with higher NF-κB phosphorylation (pNF-κB) and cardiopulmonary-derived IL-18 and NLRP3 expression. IL-18 inhibition via IL-18BP resulted in decreased cardiac pNF-κB and improved cardiac fibrosis and dysfunction in S1- or RBD-exposed hACE2 mice. Through in vivo and in vitro work, both S1 and RBD proteins induced NLRP3 inflammasome and IL-18 expression by inhibiting mitophagy and increasing mitochondrial reactive oxygenation species. Enhancing mitophagy prevented Spike protein-mediated IL-18 expression. Moreover, IL-18 inhibition reduced Spike protein-mediated pNF-κB and EC permeability. Overall, the link between reduced mitophagy and inflammasome activation represents a novel mechanism during COVID-19 pathogenesis and suggests IL-18 and mitophagy as potential therapeutic targets.

The Role of Inflammation in The Cellular and Molecular Mechanisms of Cardiopulmonary Complications of Sickle Cell Disease

Cardiopulmonary complications remain the major cause of mortality despite newer therapies and improvements in the lifespan of patients with sickle cell disease (SCD). Inflammation has been identified as a major risk modifier in the pathogenesis of SCD-associated cardiopulmonary complications in recent mechanistic and observational studies. In this review, we discuss recent cellular and molecular mechanisms of cardiopulmonary complications in SCD and summarize the most recent evidence from clinical and laboratory studies. We emphasize the role of inflammation in the onset and progression of these complications to better understand the underlying pathobiological processes. We also discuss future basic and translational research in addressing questions about the complex role of inflammation in the development of SCD cardiopulmonary complications, which may lead to promising therapies and reduce morbidity and mortality in this vulnerable population.

Are IL-1 family cytokines important in management of sickle cell disease in Sub-Saharan Africa patients?

Introduction

Sickle cell disease (SCD) is the most common genetic disease found in Africa and throughout the world. It is responsible for a high rate of hemolysis, systemic inflammation, and modulation of the immune system with the involvement of immunological molecules, such as cytokines. IL-1β is a major inflammatory cytokine. IL-18 and IL-33, members of IL-1 family, also exhibit characteristics of inflammation-related cytokines. Thus, in order to contribute to the evaluation of the severity and prognosis of SCD in Africa, this study aimed to estimate the cytokine response, in particular the levels of cytokines of the IL-1 family, in sickle cell patients living in a Sub-Saharan country.

Methods

Ninety patients with a diagnosis of SCD were recruited with different hemoglobin types. Samples were assessed for cytokine levels using the Human Inflammation Panel assay from BioLegend. The assay allows the simultaneous quantification of 13 human inflammatory cytokines/chemokines, i.e., IL-1β, IFN-α2, IFN-γ, TNFα, MCP-1 (CCL2), IL-6, IL-8 (CXCL8), IL-10, IL-12p70, IL-17A, IL-18, IL-23, and IL-33.

Results and discussion

the assessment of plasma cytokines in SCD patients revealed significantly increased levels of IL-1 family cytokines in crisis compared to steady state, suggesting a substantial involvement of these cytokines in clinical exacerbation. This suggests the possibility of a causal effect in the SCD pathology and can open the way to define better care, pointing toward new therapeutic avenues for sickle disease in Sub-Saharan Africa.

Progress of Research into the Interleukin-1 Family in Cardiovascular Disease

Inflammatory factors, such as the IL-1 family, are generally acknowledged to be involved in systemic diseases and IL-1α and IL-1β, in particular, have been linked to cardiovascular disease with IL-18, IL-33, IL-36, IL-37 and IL-38 yet to be explored. The current review aims to summarize mechanisms of IL-18, IL-33, IL-36, IL-37 and IL-38 in myocardial infarction, hypertension, arrhythmia, valvular disease and aneurysm and to explore the potential for cardiovascular disease treatment strategies and discuss future directions for prevention and treatment.

The Cardiopulmonary Complications of Sickle Cell Disease

Sickle cell disease (SCD) is a genetic hemoglobinopathy associated with extensive morbidity and early mortality. While there have been recent improvements in available disease-modifying therapies for SCD, cardiopulmonary complications remain a major risk factor for death in this population. We provide an overview of current knowledge regarding several of the major acute and chronic cardiopulmonary complications in SCD, including: acute chest syndrome, airway disease, lung function abnormalities, nocturnal hypoxemia and sleep disordered breathing, pulmonary vascular disease, and sickle cell cardiomyopathy.

Cardiovascular consequences of sickle cell disease

Sickle cell disease (SCD) is an inherited blood disorder caused by a single point mutation within the beta globin gene. As a result of this mutation, hemoglobin polymerizes under low oxygen conditions causing red blood cells to deform, become more adhesive, and increase in rigidity, which affects blood flow dynamics. This process leads to enhanced red blood cell interactions with the endothelium and contributes to vaso-occlusion formation. Although traditionally defined as a red blood cell disorder, individuals with SCD are affected by numerous clinical consequences including stroke, painful crisis episodes, bone infarctions, and several organ-specific complications. Elevated cardiac output, endothelium activation along with the sickling process, and the vaso-occlusion events pose strains on the cardiovascular system. We will present a review of the cardiovascular consequences of sickle cell disease and show connections with the vasculopathy related to SCD. We will also highlight biophysical properties and engineering tools that have been used to characterize the disease. Finally, we will discuss therapies for SCD and potential implications on SCD cardiomyopathy.

Upregulation of CCNB2 and Its Perspective Mechanisms in Cerebral Ischemic Stroke and All Subtypes of Lung Cancer: A Comprehensive Study

Cyclin B2 (CCNB2) belongs to type B cell cycle family protein, which is located on chromosome 15q22, and it binds to cyclin-dependent kinases (CDKs) to regulate their activities. In this study, 103 high-throughput datasets related to all subtypes of lung cancer (LC) and cerebral ischemic stroke (CIS) with the data of CCNB2 expression were collected. The analysis of standard mean deviation (SMD) and summary receiver operating characteristic (SROC) reflecting expression status demonstrated significant up-regulation of CCNB2 in LC and CIS (Lung adenocarcinoma: SMD = 1.40, 95%CI [0.98–1.83], SROC = 0.92, 95%CI [0.89–0.94]. Lung squamous cell carcinoma: SMD = 2.56, 95%CI [1.64–3.48]. SROC = 0.97, 95%CI [0.95–0.98]. Lung small cell carcinoma: SMD = 3.01, 95%CI [2.01–4.01]. SROC = 0.98, 95%CI [0.97–0.99]. CIS: SMD = 0.29, 95%CI [0.05–0.53], SROC = 0.68, 95%CI [0.63–0.71]). Simultaneously, protein-protein interaction (PPI) analysis indicated that CCNB2 is the hub molecule of crossed high-expressed genes in CIS and LC. Through Multiscale embedded gene co-expression network analysis (MEGENA), a gene module of CIS including 76 genes was obtained and function enrichment analysis of the CCNB2 module genes implied that CCNB2 may participate in the processes in the formation of CIS and tissue damage caused by CIS, such as “cell cycle,” “protein kinase activity,” and “glycosphingolipid biosynthesis.” Afterward, via single-cell RNA-seq analysis, CCNB2 was found up-regulated on GABAergic neurons in brain organoids as well as T cells expressing proliferative molecules in LUAD. Concurrently, the expression of CCNB2 distributed similarly to TOP2A as a module marker of cell proliferation in cell cluster. These findings can help in the field of the pathogenesis of LC-related CIS and neuron repair after CIS damage.

A cortactin CTTN coding SNP contributes to lung vascular permeability and inflammatory disease severity in African descent subjects

The cortactin gene (CTTN), encoding an actin-binding protein critically involved in cytoskeletal dynamics and endothelial cell (EC) barrier integrity, contains single nucleotide polymorphisms (SNPs) associated with severe asthma in Black patients. As loss of lung EC integrity is a major driver of mortality in the Acute Respiratory Distress Syndrome (ARDS), sepsis, and the acute chest syndrome (ACS), we speculated CTTN SNPs that alter EC barrier function will associate with clinical outcomes from these types of conditions in Black patients. In case-control studies, evaluation of a nonsynonymous CTTN coding SNP Ser484Asn (rs56162978, G/A) in a severe sepsis cohort (725 Black subjects) revealed significant association with increased risk of sepsis mortality. In a separate cohort of sickle cell disease (SCD) subjects with and without ACS (177 SCD Black subjects), significantly increased risk of ACS and increased ACS severity (need for mechanical ventilation) was observed in carriers of the A allele. Human lung EC expressing the cortactin S484N transgene exhibited: (i) delayed EC barrier recovery following thrombin-induced permeability; (ii) reduced levels of critical Tyr486 cortactin phosphorylation; (iii) inhibited binding to the cytoskeletal regulator, nmMLCK; and (iv) attenuated EC barrier-promoting lamellipodia dynamics and biophysical responses. ARDS-challenged Cttn+/- heterozygous mice exhibited increased lung vascular permeability (compared to wild-type mice) which was significantly attenuated by IV delivery of liposomes encargoed with CTTN WT transgene but not by CTTN S484N transgene. In summary, these studies suggest that the CTTN S484N coding SNP contributes to severity of inflammatory injury in Black patients, potentially via delayed vascular barrier restoration.

Structural basis of human IL-18 sequestration by the decoy receptor IL-18 binding protein (IL-18BP) in inflammation and tumor immunity

Human Interleukin-18 (IL-18) is an omnipresent proinflammatory cytokine of the IL-1 family with central roles in autoimmune and inflammatory diseases and serves as a staple biomarker in the evaluation of inflammation in physiology and disease, including the inflammatory phase of COVID-19. The sequestration of IL-18 by its soluble decoy receptor IL-18-Binding Protein (IL-18BP) is critical to the regulation of IL-18 activity. Since an imbalance in expression and circulating levels of IL-18 is associated with disease, structural insights into how IL-18BP outcompetes binding of IL-18 by its cognate cell-surface receptors are highly desirable; however, the structure of human IL-18BP in complex with IL-18 has been elusive. Here, we elucidate the sequestration mechanism of human IL-18 mediated by IL-18BP based on the crystal structure of the IL-18:IL-18BP complex. These detailed structural snapshots reveal the interaction landscape leading to the ultra-high affinity of IL-18BP toward IL-18 and identify substantial differences with respect to previously characterized complexes of IL-18 with IL-18BP of viral origin. Furthermore, our structure captured a fortuitous higher-order assembly between IL-18 and IL-18BP coordinated by a disulfide-bond distal to the binding surface connecting IL-18 and IL-18BP molecules from different complexes, resulting in a novel tetramer with 2:2 stoichiometry. This tetrapartite assembly was found to restrain IL-18 activity more effectively than the canonical 1:1 complex. Collectively, our findings provide a framework for innovative, structure-driven therapeutic strategies and further functional interrogation of IL-18 in physiology and disease.

IL-18R-mediated HSC quiescence and MLKL-dependent cell death limit hematopoiesis during infection-induced shock

Severe infection can dramatically alter blood production, but the mechanisms driving hematopoietic stem and progenitor cell (HSC/HSPC) loss have not been clearly defined. Using Ixodes ovatus Ehrlichia (IOE), a tick-borne pathogen that causes severe shock-like illness and bone marrow (BM) aplasia, type I and II interferons (IFNs) promoted loss of HSPCs via increased cell death and enforced quiescence. IFN-αβ were required for increased interleukin 18 (IL-18) expression during infection, correlating with ST-HSC loss. IL-18 deficiency prevented BM aplasia and increased HSC/HSPCs. IL-18R signaling was intrinsically required for ST-HSC quiescence, but not for HSPC cell death. To elucidate cell death mechanisms, MLKL- or gasdermin D-deficient mice were infected; whereas Mlkl^−/− mice exhibited protected HSC/HSPCs, no such protection was observed in Gsdmd^−/− mice during infection. MLKL deficiency intrinsically protected HSCs during infection and improved hematopoietic output upon recovery. These studies define MLKL and IL-18R signaling in HSC loss and suppressed hematopoietic function in shock-like infection.

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Type I and II IFNs regulate expression of IL-18 and IL-18R in shock-like infection

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IL-18 production contributes to HSC/HSPC loss during shock-like infection

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IL-18R signaling in ST-HSCs promotes infection-induced quiescence

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MLKL-deficient HSCs are protected during infection

Cardiac Chamber Quantification by Echocardiography in Adults With Sickle Cell Disease: Need Attention to Eccentric Hypertrophy

Introduction and aim

Sickle cell anemia (SCA) is the most common hemoglobinopathy worldwide, and cardiovascular diseases are the most common causes of death. In these patients, cardiac remodeling begins from childhood and leads to sickle cell cardiomyopathy in the following years. Concentric hypertrophy and eccentric hypertrophy are known to predict early cardiac events. This study aims to reveal the relationship between cardiac remodeling types and survival in patients with SCA and investigate the factors that may affect left ventricular mass.

Materials and methods

A total of 146 patients with SCA were included in the study, and the left ventricular mass index (LVMI) and relative wall thickness (RWT) of the patients were calculated according to echocardiographic measurements, and the patients were categorized into normal, concentric remodeling (CR), concentric hypertrophy (CH), and eccentric hypertrophy (EH) groups.

Results

The median age of the patients is 32 (18-72). In logistic regression analysis, hemoglobin S (HbS) and ferritin levels were independent predictors for LVMI (p = 0.01 and p < 0.001, respectively). It was observed that 56 (38.4%) of the patients had normal left ventricles, 24 (16.4%) had CR, 21 (14.4%) had CH, and 45 (30.8%) had EH. 31 (21.2%) of the patients died. When we look at the survival curves, there was a statistically significant difference between the four groups (log-rank p < 0.001). It was observed that patients with EH were the group with the lowest probability of survival.

Conclusion

Cardiac death is one of the most common causes of death in patients with SCA. Early detection of cardiac disorders and starting treatment may be important in reducing mortality in these patients.