Clinical efficacy and safety of interleukin-1 blockade in the treatment of patients with COVID-19: a systematic review and meta-analysis of randomized controlled trials.

OBJECTIVE: This study evaluated the clinical efficacy and safety of interleukin-1 (IL-1) blockade for patients with COVID-19. METHODS: The PubMed, Web of Science, Ovid Medline, Embase and Cochrane Library databases were searched for relevant articles from their inception to 25 September 2022. Only randomized clinical trials (RCTs) that assessed the clinical efficacy and safety of IL-1 blockade in the treatment of patients with COVID-19 were included. RESULTS: This meta-analysis included seven RCTs. No significant difference in the all-cause mortality rate of patients with COVID-19 was observed between the IL-1 blockade and control groups (7.7 vs. 10.5%, odds ratio [OR] = 0.83, 95% confidence interval [CI] 0.57-1.22; I2 = 18%). However, the study group was at significantly lower risk of requiring mechanical ventilation (MV) compared with the control group (OR = 0.53, 95% CI 0.32-0.86; I2 = 24%). Finally, the risk of adverse events was similar between the two groups. CONCLUSIONS: IL-1 blockade does not provide increased survival benefits in hospitalized patients with COVID-19, but it may reduce the need for MV. Furthermore, it is a safe agent for use in the treatment of COVID-19.>.

This systematic review and meta-analysis of randomized clinical trials (RCTs) evaluated the clinical efficacy and safety of interleukin-1 (IL-1) blockade for patients with COVID-19.Based on the analysis of six RCTs, no significant difference in the all-cause mortality rate of patients with COVID-19 was observed between the IL-1 blockade and control groups.The study group using IL1 was associated with a significantly lower risk of requiring mechanical ventilation compared with the control group.The risk of adverse events was similar between the study and the control groups.

The roles of critical pro-inflammatory cytokines in the drive of cytokine storm during SARS-CoV-2 infection.

In patients with severe COVID-19, acute respiratory distress syndrome (ARDS), multiple organ dysfunction syndrome (MODS), and even mortality can result from cytokine storm, which is a hyperinflammatory medical condition caused by the excessive and uncontrolled release of pro-inflammatory cytokines. High levels of numerous crucial pro-inflammatory cytokines, such as interleukin-1 (IL-1), IL-2, IL-6, tumor necrosis factor-α, interferon (IFN)-γ, IFN-induced protein 10 kDa, granulocyte-macrophage colony-stimulating factor, monocyte chemoattractant protein-1, and IL-10 and so on, have been found in severe COVID-19. They participate in cascade amplification pathways of pro-inflammatory responses through complex inflammatory networks. Here, we review the involvements of these critical inflammatory cytokines in SARS-CoV-2 infection and discuss their potential roles in triggering or regulating cytokine storm, which can help to understand the pathogenesis of severe COVID-19. So far, there is rarely effective therapeutic strategy for patients with cytokine storm besides using glucocorticoids, which is proved to result in fatal side effects. Clarifying the roles of key involved cytokines in the complex inflammatory network of cytokine storm will help to develop an ideal therapeutic intervention, such as neutralizing antibody of certain cytokine or inhibitor of some inflammatory signal pathways.

The Role of Inflammatory Cytokines (Interleukin-1 and Interleukin-6) as a Potential Biomarker in the Different Stages of COVID-19 (Mild, Severe, and Critical).

Cytokine storm refers to the overproduction of immune and inflammatory cells and their proteins (cytokines) [interleukin (IL)-1 and IL-6] causing acute respiratory distress syndrome in COVID-19. COVID-19 causes inflammatory reactions, and patients with COVID-19 had categorized as mild, severe, and critical after reviewing previous studies. Then, it is crucial to find immune-inflammatory indicators that might predict the disorder severity and the prognosis primarily for guiding medical therapy in the face of this unexpectedly developing unique infectious disease. Higher levels of IL-6 and IL-1 levels might be seen in patients with COVID-19 at each stage. In addition, IL-1-induced IL-6 assists in the synthesis of liver C-reactive protein (CRP) in acute phase responses. Recent studies suggested that IL-6 levels are an independent predictor of COVID-19 illness because they were significantly higher in patients with severe than with mild COVID-19 symptoms. Anakinra and tocilizumab (TCZ) are beneficial in lowing mortality in COVID-19 patients; however, information on their safety and efficacy is scarce. The aim of this study was to investigate the role of inflammatory cytokines (IL-1 and IL-6) as potential biomarkers in the different stages (mild, severe, and critical) of COVID-19. A systematic search during the years 2021-2022 using the keywords SARS-CoV-2, COVID-19, IL-6, IL-1, CRP, mild stage, severe stage, critical stage, cytokine storm, tocilizumab, and anakinra was performed in PubMed and Google Scholar databases. This study reviews studies that have investigated the role of high levels of these cytokines in the severity of the disease in patients with COVID-19 and the inhibitory function of TCZ and anakinra in preventing mechanical ventilation and patient mortality. According to the result, studies suggest that decreased innate immune response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in association with the production of inflammatory cytokines is the determining and driving function of COVID-19.

Selected Phytochemicals to Combat Lungs Injury: Natural Care.

The human has two lungs responsible for respiration and drug metabolism. Severe lung infection caused by bacteria, mycobacteria, viruses, fungi, and parasites may lead to lungs injury. Smoking and tobacco consumption may also produce lungs injury. Inflammatory and pain mediators are secreted by alveolar macrophages. The inflammatory mediators, such as cytokines, interleukin (IL)-1, IL-6, IL-8, IL-10, and tumor necrosis factor (TNF)-α, neutrophils, and fibroblasts are accumulated in the alveoli sac, which becomes infected. It may lead to hypoxia followed by severe pulmonary congestion and the death of the patient. There is an urgent need for the treatment of artificial respiration and ventilation. However, the situation may be the worst for patients suffering from lung cancer, pulmonary tuberculosis, and acute pneumonia caused by acute respiratory distress syndrome (ARDS). Re-urgency has been happening in the case of coronavirus disease of 2019 (COVID-19) patients. Therefore, it is needed to protect the lungs with the intake of natural phytomedicines. In the present review, several selected phyto components having the potential role in lung injury therapy have been discussed. Regular intake of natural vegetables and fruits bearing these constituents may save the lungs even in the dangerous attack of SARS-CoV-2 in lung cancer, pulmonary TB, and pneumatic patients.

Study of frequency and inheritance model of ACE1 I/D and ACE2 rs2285666 polymorphisms in COVID-19 patients with varying severity of lung involvement and its effect on serum cytokines levels.

The angiotensin-converting enzyme (ACE) has been shown to play a role as a receptor for the COVID-19 virus. This virus usually gets into cells and infects them by attaching to their glycoprotein receptors, which are found on the ACE2 receptor. The aim of this study was to evaluate the frequency and inheritance of ACE1 I/D and ACE2 rs2285666 polymorphisms in COVID-19 patients with varying severity of lung involvement and its effect on serum cytokines levels of interleukin (IL)-1 and IL-6 and laboratory parameters. One hundred eighty-five COVID-19 patients were grouped according to the severity of lung involvement. (I/D) polymorphism of the ACE1 gene and rs2285666 polymorphism of the ACE2 gene were determined by single specific primer-polymerase chain reaction and restriction fragment length reaction-polymerase chain reaction methods, respectively. Serum levels of IL-1 and IL-6 were also measured by the enzyme linked immunosorbent assay technique. No statistically significant association of ACE2 rs2285666 polymorphism genotypes and ACE1 I/D with the severity of lung involvement was noted. However, there was a statistically significant association between I/D ACE1 polymorphism genotypes and IL-6, white blood cells (WBC), and neutrophil-to-lymphocyte ratio (NLR) levels. Also, there was no statistically significant association between rs2285666 polymorphism genotypes and patients' blood oxygen saturation level, IL-6, IL-1ß, lactate dehydrogenase activity, WBC count, and NLR. In patients with COVID-19, the rs2285666 polymorphism of the ACE2 gene and the I/D polymorphism of the ACE1 gene were not significantly associated with the severity of COVID-19 disease and serum IL-6 and IL-1 cytokine levels.

Adult-Onset Still's Disease-A Complex Disease, a Challenging Treatment.

Adult-onset Still's disease (AOSD) is a systemic inflammatory disorder with an unknown cause characterized by high-spiking fever, lymphadenopathy, hepatosplenomegaly, hyperferritinemia, and leukocytosis. The clinical course can be divided into three significant patterns, each with a different prognosis: Self-limited or monophasic, intermittent or polycyclic systemic, and chronic articular. Two criteria sets have been validated. The Yamaguchi criteria are the most generally used, although the Fautrel criteria offer the benefit of adding ferritin and glycosylated ferritin values. AOSD's pathogenesis is not yet completely understood. Chemokines and pro-inflammatory cytokines, including interferon (IFN)-γ, tumor necrosis factor α (TNFα), interleukin (IL)-1, IL-6, IL-8, and IL-18, play a crucial role in the progression of illness, resulting in the development of innovative targeted therapeutics. There are no treatment guidelines for AOSD due to its rarity, absence of controlled research, and lack of a standard definition for remission and therapy objectives. Non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids (CS), and conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) are used in AOSD treatment. Biological therapy, including IL-1, IL-6, IL-18, and IL-17 inhibitors, as well as TNFα or Janus-kinases (JAKs) inhibitors, is administered to patients who do not react to CS and csDMARDs or achieve an inadequate response.

Efficacy of anticytokine treatments added to corticosteroids in patients with COVID-19-associated pneumonia and hyperinflammation: a single center experience.

OBJECTIVE: Pneumonia and hyperinflammatory state related to COVID-19 infection are fatal clinical conditions without definite treatment modalities. Interleukin-6 and Interleukin-1 targeted therapies have been proposed as treatment options. This study was conducted to investigate the efficacy of anakinra and tocilizumab added to corticosteroids in patients with COVID-19-associated pneumonia and hyper-inflammatory syndrome in our tertiary clinical center. PATIENTS AND METHODS: Patients with COVID-19-associated pneumonia and hyperinflammatory state who did not respond to initial treatments, including corticosteroids, were included in the study. The patients' electronic records were reviewed retrospectively and recorded according to a standardized data table. Univariate and multivariate regression analyses were used to identify risk factors associated with intubation. RESULTS: 388 patients were included in the study. 197 patients were intubated and most of them died (n=194/197, 98%). 67 patients received tocilizumab, and 97 patients received anakinra. Anakinra [OR: 0.440, 95% CI=0.244-0.794, p=0.006] and tocilizumab [OR: 0.491, 95% CI=0.256-0.943, p=0.033] were both associated with a decreased risk for intubation. However, having a neutrophil/lymphocyte ratio ≥ 10 [OR: 2.035, 95% CI=1.143-3.623, p=0.016], serum lactate dehydrogenase (LDH) level ≥ 400 [OR: 3.160, 95% CI=1.937-5.156, p<0.001] and age ≥ 50 [OR: 4.048, 95% CI=2.037-8.043, p < 0.001] was associated with an increased risk for intubation. CONCLUSIONS: Both anakinra and tocilizumab, added to initial standard COVID-19 treatments (including glucocorticoids) reduced the need for intubation in patients with COVID-19-associated severe pneumonia and hyperinflammatory syndrome. Given the high mortality rate of intubated patients with COVID-19, both treatments may have added benefits on mortality.

Evaluation of Cardiac Biomarkers and Expression Analysis of IL-1, IL-6, IL-10, IL-17, and IL-25 among COVID-19 Patients from Pakistan.

Coronavirus disease 19 (COVID-19) is caused by viral infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Where upregulation of several important biomarkers and multiple organ dysfunction occurs, this study aimed to evaluate the association of cardiac biomarkers and CS induced acute lung damage with disease severity and mortality in survival of COVID-19 patients. A total of 500 COVID-19 patients with elevated cardiac biomarkers were studied for the analysis of myocardial abnormality through cardiac enzymes, inflammatory biomarkers, and the expression analysis of various cytokines, including IL-1, IL-6, IL-10, IL-17, and IL-25 genes. The elevation of various cardiac enzymes including LDH (87%), CK (78.4%), TNI (80.4%), CK-MB (83%), and D-dimer (80.8%) were found correlated (p < 0.001) with COVID-19 infection. Cardiac enzyme elevation was highly associated with an increased level of inflammatory biomarkers such as CRP (14.2%), SAA (11.4%) and erythrocyte sedimentation rate (ESR) (7.8%) (p = 0.001 for all). The quantitative expression analysis of IL-10, 1L-17, and 1L-25 were found to be high, while those of IL-1 and IL-6 were moderately elevated. The death-to-live ratio of COVID-19 patients was 457:43 indicating that the patients having elevated levels of both CKMB, D-dimer, CK and IL-1, IL-6, IL-10 and D-dimer, Troponin, CK and IL-1, IL-10 had high fatality rate (73% and 12% respectively). The current finding concludes that the evaluation of cardiac biomarkers with cytokine storm plays a significant role in COVID-19-associated anatomical organ damage, myocardial injury, and mortality. Physicians should pay special attention to cardiac biomarkers in patients with old age, inflammation, and comorbidities among COVID-19 infections.

The role of IL-36 subfamily in intestinal disease.

Interleukin (IL)-36 is a subfamily, of the IL-1 super-family and includes IL-36α, IL-36ß, IL-36γ, IL-38 and IL-36Ra. IL-36 cytokines are involved in the pathology of multiple tissues, including skin, lung, oral cavity, intestine, kidneys and joints. Recent studies suggest that IL-36 signaling regulates autoimmune disease in addition to antibacterial and antiviral responses. Most research has focused on IL-36 in skin diseases such as psoriasis, however, studies on intestinal diseases are also underway. This review outlines what is known about the bioactivity of the IL-36 subfamily and its role in the pathogenesis of intestinal diseases such as inflammatory bowel disease, colorectal cancer, gut dysbacteriosis and infection, and proposes that IL-36 may be a target for novel therapeutic strategies to prevent or treat intestinal diseases.

Inflammasomes and IL-1 family cytokines in SARS-CoV-2 infection: from prognostic marker to therapeutic agent.

Despite global vaccination programs, infections with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) continue to cause severe disease with significant morbidity and mortality. Severe coronavirus disease 2019 (COVID-19) is characterized by an exuberant inflammatory response in the lung leading to acute lung injury and consequent gas exchange problems. Complete insights in this hyperinflammatory response are still lacking. However, a thorough understanding of immunopathogenesis of severe COVID-19 is needed to not only develop personalized targeted therapies, but also to identify biomarkers that predict disease outcome and therapeutic responses. Here we review the current evidence that SARS-CoV-2 activates the inflammasome, which is an intracellular multiprotein complex that leads to the activation and secretion of the interleukin (IL)-1 family cytokines, IL-1ß and IL-18, and to a lytic form of cell death, called pyroptosis. Further we discuss the contribution of inflammasomes and IL-1 family cytokines to the immunopathogenesis of COVID-19 and its clinical implications.

Current evidence on the use of anakinra in COVID-19.

Despite the progressing knowledge in COVID-19 management, remdesivir is the only agent that got approval to inhibit viral replication. However, there are limited data about effective immunomodulatory agents to prevent cytokine release in COVID-19. Cytokine release syndrome in COVID-19 resembles secondary hemophagocytic lymphohistiocytosis, in which interleukin-1 (IL-1) plays a key role. Anakinra is the first recombinant IL-1 receptor antagonist studied for off-label use in COVID-19 treatment. This study reviews the current clinical evidence on the role of interleukin-1 in COVID-19-related cytokine storm, therapeutic effects, significant clinical concerns, and pros and cons of anakinra administration in the management of COVID-19 patients. In this review, four items are shown to be important for achieving the optimal therapeutic effects of anakinra in COVID-19 patients. These items include duration of treatment ≥ 10 days, doses ≥ 100 mg, intravenous administration, and early initiation of therapy. Also, anakinra might be more beneficial in the early stages of the disease when higher levels of cytokines are yet to be observed, which could prevent progression to severe illness and mechanical ventilation. Further studies are required to address the SARS-CoV-2 induced cytokine release syndrome and the role of anakinra in identifying ideal treatment approaches for COVID-19 patients based on their clinical status.

Biologic disease-modifying antirheumatic drugs to treat multisystem inflammatory syndrome in children.

PURPOSE OF REVIEW: Multisystem inflammatory syndrome in children (MIS-C) is a postinfectious complication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection primarily affecting children. MIS-C shares features with Kawasaki disease (KD) and cytokine storm syndrome (CSS) frequently requiring intensive care support. Although intravenous immunoglobulin (IVIg) and glucocorticoids (GCs) are effective therapeutics for most, refractory MIS-C is treated with various biologic disease-modifying antirheumatic drugs (bDMARDs). Understanding the clinical features, inflammatory cytokines, and genetic associations provides rationale for bDMARD in treating severe MIS-C. RECENT FINDINGS: Children with MIS-C have clinical KD features and often present in hypovolemic and cardiogenic shock requiring volume repletion (gastrointestinaI losses) and cardiac pressor support (epinephrine). Investigation of MIS-C serum reveals elevated pro-inflammatory cytokines [interleukin (IL)-1, IL-6, IL-18, interferon gamma (IFNγ), tumor necrosis factor (TNF)], but to a lesser extent than other established CSS. Gene sequencing of MIS-C children identifies heterozygous mutations in CSS associated genes. Treatment of refractory (IVIg and GC) MIS-C with bDMARDs to IL-1, IL-6, and TNF is efficacious for survival as well as resolving cardiac and coronary artery inflammation. SUMMARY: MIS-C is a postinfectious complication of SARS-CoV-2 resembling KD and CSS, both genetically and by pro-inflammatory cytokines. MIS-C that is refractory to IVIg and GC is routinely responsive to bDMARDs targeting IL-1, IL-6, and TNF.

The role of IL-1 family of cytokines and receptors in pathogenesis of COVID-19.

A global pandemic has erupted as a result of the new brand coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This pandemic has been consociated with widespread mortality worldwide. The antiviral immune response is an imperative factor in confronting the recent coronavirus disease 2019 (COVID-19) infections. Meantime, cytokines recognize as crucial components in guiding the appropriate immune pathways in the restraining and eradication of the virus. Moreover, SARS-CoV-2 can induce uncontrolled inflammatory responses characterized by hyper-inflammatory cytokine production, which causes cytokine storm and acute respiratory distress syndrome (ARDS). As excessive inflammatory responses are contributed to the severe stage of the COVID-19 disease, therefore, the pro-inflammatory cytokines are regarded as the Achilles heel during COVID-19 infection. Among these cytokines, interleukin (IL-) 1 family cytokines (IL-1, IL-18, IL-33, IL-36, IL-37, and IL-38) appear to have a strong inflammatory role in severe COVID-19. Hence, understanding the underlying inflammatory mechanism of these cytokines during infection is critical for reducing the symptoms and severity of the disease. Here, the possible mechanisms and pathways involved in inflammatory immune responses are discussed.

Rationale and design of interleukin-1 blockade in recently decompensated heart failure (REDHART2): a randomized, double blind, placebo controlled, single center, phase 2 study.

BACKGROUND: Heart failure (HF) is a global leading cause of mortality despite implementation of guideline directed therapy which warrants a need for novel treatment strategies. Proof-of-concept clinical trials of anakinra, a recombinant human Interleukin-1 (IL-1) receptor antagonist, have shown promising results in patients with HF. METHOD: We designed a single center, randomized, placebo controlled, double-blind phase II randomized clinical trial. One hundred and two adult patients hospitalized within 2 weeks of discharge due to acute decompensated HF with reduced ejection fraction (HFrEF) and systemic inflammation (high sensitivity of C-reactive protein > 2 mg/L) will be randomized in 2:1 ratio to receive anakinra or placebo for 24 weeks. The primary objective is to determine the effect of anakinra on peak oxygen consumption (VO2) measured at cardiopulmonary exercise testing (CPX) after 24 weeks of treatment, with placebo-corrected changes in peak VO2 at CPX after 24 weeks (or longest available follow up). Secondary exploratory endpoints will assess the effects of anakinra on additional CPX parameters, structural and functional echocardiographic data, noninvasive hemodynamic, quality of life questionnaires, biomarkers, and HF outcomes. DISCUSSION: The current trial will assess the effects of IL-1 blockade with anakinra for 24 weeks on cardiorespiratory fitness in patients with recent hospitalization due to acute decompensated HFrEF. TRIAL REGISTRATION: The trial was registered prospectively with ClinicalTrials.gov on Jan 8, 2019, identifier NCT03797001.

Inflammasome activation in infected macrophages drives COVID-19 pathology.

Severe COVID-19 is characterized by persistent lung inflammation, inflammatory cytokine production, viral RNA and a sustained interferon (IFN) response, all of which are recapitulated and required for pathology in the SARS-CoV-2-infected MISTRG6-hACE2 humanized mouse model of COVID-19, which has a human immune system1-20. Blocking either viral replication with remdesivir21-23 or the downstream IFN-stimulated cascade with anti-IFNAR2 antibodies in vivo in the chronic stages of disease attenuates the overactive immune inflammatory response, especially inflammatory macrophages. Here we show that SARS-CoV-2 infection and replication in lung-resident human macrophages is a critical driver of disease. In response to infection mediated by CD16 and ACE2 receptors, human macrophages activate inflammasomes, release interleukin 1 (IL-1) and IL-18, and undergo pyroptosis, thereby contributing to the hyperinflammatory state of the lungs. Inflammasome activation and the accompanying inflammatory response are necessary for lung inflammation, as inhibition of the NLRP3 inflammasome pathway reverses chronic lung pathology. Notably, this blockade of inflammasome activation leads to the release of infectious virus by the infected macrophages. Thus, inflammasomes oppose host infection by SARS-CoV-2 through the production of inflammatory cytokines and suicide by pyroptosis to prevent a productive viral cycle.

Immunotherapy of COVID-19: Inside and Beyond IL-6 Signalling.

Acting on the cytokine cascade is key to preventing disease progression and death in hospitalised patients with COVID-19. Among anti-cytokine therapies, interleukin (IL)-6 inhibitors have been the most used and studied since the beginning of the pandemic. Going through previous observational studies, subsequent randomised controlled trials, and meta-analyses, we focused on the baseline characteristics of the patients recruited, identifying the most favourable features in the light of positive or negative study outcomes; taking into account the biological significance and predictivity of IL-6 and other biomarkers according to specific thresholds, we ultimately attempted to delineate precise windows for therapeutic intervention. By stimulating scavenger macrophages and T-cell responsivity, IL-6 seems protective against viral replication during asymptomatic infection; still protective on early tissue damage by modulating the release of granzymes and lymphokines in mild-moderate disease; importantly pathogenic in severe disease by inducing the proinflammatory activation of immune and endothelial cells (through trans-signalling and trans-presentation); and again protective in critical disease by exerting homeostatic roles for tissue repair (through cis-signalling), while IL-1 still drives hyperinflammation. IL-6 inhibitors, particularly anti-IL-6R monoclonal antibodies (e.g., tocilizumab, sarilumab), are effective in severe disease, characterised by baseline IL-6 concentrations ranging from 35 to 90 ng/mL (reached in the circulation within 6 days of hospital admission), a ratio of partial pressure arterial oxygen (PaO2) and fraction of inspired oxygen (FiO2) between 100 and 200 mmHg, requirement of high-flow oxygen or non-invasive ventilation, C-reactive protein levels between 120 and 160 mg/L, ferritin levels between 800 and 1600 ng/mL, D-dimer levels between 750 and 3000 ng/mL, and lactate dehydrogenase levels between 350 and 500 U/L. Granulocyte-macrophage colony-stimulating factor inhibitors might have similar windows of opportunity but different age preferences compared to IL-6 inhibitors (over or under 70 years old, respectively). Janus kinase inhibitors (e.g., baricitinib) may also be effective in moderate disease, whereas IL-1 inhibitors (e.g., anakinra) may also be effective in critical disease. Correct use of biologics based on therapeutic windows is essential for successful outcomes and could inform future new trials with more appropriate recruiting criteria.

IL-1 and IL-1ra are key regulators of the inflammatory response to RNA vaccines.

The use of lipid-formulated RNA vaccines for cancer or COVID-19 is associated with dose-limiting systemic inflammatory responses in humans that were not predicted from preclinical studies. Here, we show that the 'interleukin 1 (IL-1)-interleukin 1 receptor antagonist (IL-1ra)' axis regulates vaccine-mediated systemic inflammation in a host-specific manner. In human immune cells, RNA vaccines induce production of IL-1 cytokines, predominantly IL-1ß, which is dependent on both the RNA and lipid formulation. IL-1 in turn triggers the induction of the broad spectrum of pro-inflammatory cytokines (including IL-6). Unlike humans, murine leukocytes respond to RNA vaccines by upregulating anti-inflammatory IL-1ra relative to IL-1 (predominantly IL-1α), protecting mice from cytokine-mediated toxicities at >1,000-fold higher vaccine doses. Thus, the IL-1 pathway plays a key role in triggering RNA vaccine-associated innate signaling, an effect that was unexpectedly amplified by certain lipids used in vaccine formulations incorporating N1-methyl-pseudouridine-modified RNA to reduce activation of Toll-like receptor signaling.