Critical imbalance of TNF-α and soluble TNF receptor 1 in a patient with macrophage activation syndrome: potential implications for diagnostics and treatment

The Role of the IL-33/ST2 Axis in CpG-Induced Macrophage Activation Syndrome

Background

Macrophage activation syndrome (MAS) is a fatal inflammatory condition, which is often associated with the elevation of multiple proinflammatory cytokines and multiple organ dysfunction. Previous studies have shown that ST2 contributes to T cell overactivation and plays a detrimental role in mouse models of primary hemophagocytic lymphohistiocytosis. The purpose of this study was to investigate the role of the IL-33/ST2 axis in a mouse model of MAS induced by repeated injections of cytosine-phosphate-guanine (CpG).

Methods

Serum cytokines were determined using the cytometric bead array by flow cytometry. IL-33 and ST2 were detected by immunohistochemistry and real-time quantitative PCR in the liver and spleen of mice. CD3 and F4/80 in the liver were detected by immunohistochemistry. Inflammatory macrophages and effector memory T lymphocytes were detected by flow cytometry.

Result

The CpG-induced MAS model was successfully induced after repeated CpG injections, presenting with hypercytokinemia and hepatosplenomegaly. The numbers of IL-33 positive cells in the liver and spleen decreased significantly, while the expression of ST2 in the liver tended to increase in the mice with MAS. IL-33 and St2 knockout mice showed similar levels of hepatosplenomegaly, peripheral blood count, and cytokine storm when compared with wild-type (WT) mice after induction of MAS. There were also no significant differences in liver pathology (including inflammatory cell infiltration of CD3 and F4/80) and levels of splenic inflammatory macrophages and effector memory T cells between the WT and knockout mice.

Conclusion

These results suggested that IL-33 decreased in the liver and spleen tissues of MAS mice. Further results suggest that IL-33 and St2 knockout mice have no treatment potential in CpG-induced MAS. Thus, the IL-33/ST2 axis has little effect on the prognosis of CpG-induced MAS.

Clinical Symptoms, Laboratory Parameters and Long-Term Follow-up in a National DADA2 Cohort

Deficiency of adenosine deaminase-2 (DADA2) is an autosomal recessive autoinflammatory disease with an extremely variable disease presentation. This paper provides a comprehensive overview of the Dutch DADA2 cohort. We performed a retrospective cohort study in 29 ADA2-deficient patients from 23 families with a median age at inclusion of 26 years. All patients had biallelic pathogenic variants in the ADA2 gene. The most common clinical findings included cutaneous involvement (79.3%), (hepato)splenomegaly (70.8%) and recurrent infections (58.6%). Stroke was observed in 41.4% of the patients. The main laboratory abnormalities were hypogammaglobulinemia and various cytopenias. Patients presented most often with a mixed phenotype involving vasculopathy, immunodeficiency and hematologic manifestations (62.1%). In this cohort, malignancies were reported in eight patients (27.6%), of whom five presented with a hematologic malignancy and two with a basal cell carcinoma. Four patients developed hemophagocytic lymphohistiocytosis (HLH) or an HLH-like episode, of whom three passed away during or shortly after the occurrence of HLH. TNF-inhibitors (TNFi) were effective in treating vasculopathy-associated symptoms and preventing stroke, but were hardly effective in the treatment of hematologic manifestations. Three patients underwent hematopoietic cell transplantation and two of them are doing well with complete resolution of DADA2-related symptoms. The overall mortality in this cohort was 17.2%. In conclusion, this cohort describes the clinical, genetic and laboratory findings of 29 Dutch DADA2 patients. We describe the occurrence of HLH as a life-threatening disease complication and report a relatively high incidence of malignancies and mortality.

Biological therapies for hemophagocytic lymphohistiocytosis: current knowledge and future perspectives

INTRODUCTION

Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome with a dismal prognosis. The underlying causes of HLH are diverse. However, the overabundance of cytokines was shared by all forms of HLH. Cytokine-targeted biotherapies have been increasingly used in HLH treatment.

AREAS COVERED

In this review, we aim to provide an overview of biological treatment options for HLH.

EXPERT OPINION

Biological therapies offer alternative treatment options for patients with refractory/relapsed HLH or who are intolerant to conventional chemotherapies. As a complement to traditional treatment, biological agents improve response rates, maintain more protracted periods of remission, and reduce treatment related toxicity. A combination of biological agents may be a promising direction for HLH treatment. However, they may induce HLH to deteriorate and even trigger HLH.

Looking into the IL-1 of the storm: are inflammasomes the link between immunothrombosis and hyperinflammation in cytokine storm syndromes?

Inflammasomes and the interleukin (IL)-1 family of cytokines are key mediators of both inflammation and immunothrombosis. Inflammasomes are responsible for the release of the pro-inflammatory cytokines IL-1β and IL-18, as well as releasing tissue factor (TF), a pivotal initiator of the extrinsic coagulation cascade. Uncontrolled production of inflammatory cytokines results in what is known as a "cytokine storm" leading to hyperinflammatory disease. Cytokine storms can complicate a variety of diseases and results in hypercytokinemia, coagulopathies, tissue damage, multiorgan failure, and death. Patients presenting with cytokine storm syndromes have a high mortality rate, driven in part by disseminated intravascular coagulation (DIC). While our knowledge on the factors propagating cytokine storms is increasing, how cytokine storm influences DIC remains unknown, and therefore treatments for diseases, where these aspects are a key feature are limited, with most targeting specific cytokines. Currently, no therapies target the immunothrombosis aspect of hyperinflammatory syndromes. Here we discuss how targeting the inflammasome and pyroptosis may be a novel therapeutic strategy for the treatment of hyperinflammation and its associated pathologies.

Targeting TNF-α for COVID-19: Recent Advanced and Controversies

Recent advances in the pathophysiologic understanding of coronavirus disease 2019 (COVID-19) suggests that cytokine release syndrome (CRS) has an association with the severity of disease, which is characterized by increased tumor necrosis factor α (TNF-α), interleukin (IL)-6, IL-2, IL-7, and IL-10. Hence, managing CRS has been recommended for rescuing severe COVID-19 patients. TNF-α, one of the pro-inflammatory cytokines commonly upregulated in acute lung injury, triggers CRS and facilitates SARS-CoV-2 interaction with angiotensin-converting enzyme 2 (ACE2). TNF-α inhibitors, therefore, may serve as an effective therapeutic strategy for attenuating disease progression in severe SARS-CoV-2 infection. Below, we review the possibilities and challenges of targeting the TNF-α pathway in COVID-19 treatment.

Long-term surveillance of biologic therapies in systemic-onset juvenile idiopathic arthritis: data from the German BIKER registry

OBJECTIVE

Using data from the German Biologics JIA Registry (BIKER), long-term safety of biologics for systemic-onset JIA with regard to adverse events of special interest was assessed.

METHODS

Safety assessments were based on adverse event reports after first dose through 90 days after last dose. Rates of adverse event, serious adverse event and 25 predefined adverse events of special interest were analysed. Incidence rates were compared for each biologic against all other biologics combined applying a mixed-effect Poisson model.

RESULTS

Of 260 systemic-onset JIA patients in this analysis, 151 patients received etanercept, 109 tocilizumab, 71 anakinra and 51 canakinumab. Patients with etanercept had higher clinical Juvenile Arthritis Disease Activity Score 10 scores, active joint counts and steroid use at therapy start. Serious adverse events were reported with higher frequency in patients receiving canakinumab [20/100 patient years (PY)] and tocilizumab (21/100 PY). Cytopenia and hepatic events occurred with a higher frequency with tocilizumab and canakinumab. Medically important infections were seen more often in patients with IL-6 or IL-1 inhibition. Macrophage activation syndrome occurred in all cohorts with a higher frequency in patients with canakinumab (3.2/100 PY) and tocilizumab (2.5/100 PY) vs anakinra (0.83/100 PY) and etanercept (0.5/100 PY). After adjustment only an elevated risk for infections in anakinra-treated patients remained significant. Three definite malignancies were reported in patients ever exposed to biologics. Two deaths occurred in patients treated with etanercept.

CONCLUSION

Surveillance of pharmacotherapy as provided by BIKER is an import approach especially for patients on long-term treatment. Overall, tolerance was acceptable. Differences between several biologics were noted and should be considered in daily patient care.

Coronavirus disease 2019: investigational therapies in the prevention and treatment of hyperinflammation

Introduction: The mortality of coronavirus disease 2019 (COVID-19) is frequently driven by an injurious immune response characterized by the development of acute respiratory distress syndrome (ARDS), endotheliitis, coagulopathy, and multi-organ failure. This spectrum of hyperinflammation in COVID-19 is commonly referred to as cytokine storm syndrome (CSS). Areas covered: Medline and Google Scholar were searched up until 15th of August 2020 for relevant literature. Evidence supports a role of dysregulated immune responses in the immunopathogenesis of severe COVID-19. CSS associated with SARS-CoV-2 shows similarities to the exuberant cytokine production in some patients with viral infection (e.g.SARS-CoV-1) and may be confused with other syndromes of hyperinflammation like the cytokine release syndrome (CRS) in CAR-T cell therapy. Interleukin (IL)-6, IL-8, and tumor necrosis factor-alpha have emerged as predictors of COVID-19 severity and in-hospital mortality. Expert opinion: Despite similarities, COVID-19-CSS appears to be distinct from HLH, MAS, and CRS, and the application of HLH diagnostic scores and criteria to COVID-19 is not supported by emerging data. While immunosuppressive therapy with glucocorticoids has shown a mortality benefit, cytokine inhibitors may hold promise as 'rescue therapies' in severe COVID-19. Given the arguably limited benefit in advanced disease, strategies to prevent the development of COVID-19-CSS are needed.

CD3 bispecific antibody-induced cytokine release is dispensable for cytotoxic T cell activity

T cell-retargeting therapies have transformed the therapeutic landscape of oncology. Regardless of the modality, T cell activating therapies are commonly accompanied by systemic cytokine release, which can progress to deadly cytokine release syndrome (CRS). Because of incomplete mechanistic understanding of the relationship between T cell activation and systemic cytokine release, optimal toxicity management that retains full therapeutic potential remains unclear. Here, we report the cell type-specific cellular mechanisms that link CD3 bispecific antibody-mediated killing to toxic cytokine release. The immunologic cascade is initiated by T cell triggering, whereas monocytes and macrophages are the primary source of systemic toxic cytokine release. We demonstrate that T cell-generated tumor necrosis factor-α (TNF-α) is the primary mechanism mediating monocyte activation and systemic cytokine release after CD3 bispecific treatment. Prevention of TNF-α release is sufficient to impair systemic release of monocyte cytokines without affecting antitumor efficacy. Systemic cytokine release is only observed upon initial exposure to CD3 bispecific antibody not subsequent doses, indicating a biological distinction between doses. Despite impaired cytokine release after second exposure, T cell cytotoxicity remained unaffected, demonstrating that cytolytic activity of T cells can be achieved in the absence of cytokine release. The mechanistic uncoupling of toxic cytokines and T cell cytolytic activity in the context of CD3 bispecifics provides a biological rationale to clinically explore preventative treatment approaches to mitigate toxicity.

Macrophage activation syndrome and COVID-19

An emerging, rapidly spreading coronavirus SARS-CoV-2 is causing a devastating pandemic. As we have not developed curative medicine and effective vaccine, the end of this life-threatening infectious disease is still unclear. Severe COVID-19 is often associated with hypercytokinemia, which is typically found in macrophage activation syndrome. SARS-CoV-2 infection causes this strong inflammation within the lung and propagates to respiratory and, ultimately, systemic organ malfunction. Although we have not fully understood the physiological and pathological aspects of COVID-19, current research progress indicates the effectiveness of anti-cytokine therapy. Here, we summarize macrophage activation syndrome and its possible contribution to COVID-19, and cytokine targeted attempts in severe COVID-19 cases.

Should we stimulate or suppress immune responses in COVID-19? Cytokine and anti-cytokine interventions

The coronavirus disease-19 pandemic (COVID-19), which appeared in China in December 2019 and rapidly spread throughout the world, has forced clinicians and scientists to take up extraordinary challenges. This unprecedented situation led to the inception of numerous fundamental research protocols and many clinical trials. It quickly became apparent that although COVID-19, in the vast majority of cases, was a benign disease, it could also develop a severe form with sometimes fatal outcomes. Cytokines are central to the pathophysiology of COVID-19; while some of them are beneficial (type-I interferon, interleukin-7), others appear detrimental (interleukin-1β, -6, and TNF-α) particularly in the context of the so-called cytokine storm. Yet another characteristic of the disease has emerged: concomitant immunodeficiency, notably involving impaired type-I interferon response, and lymphopenia. This review provides an overview of current knowledge on COVID-19 immunopathology. We discuss the defective type-I IFN response, the theoretical role of IL-7 to restore lymphocyte repertoire, as well as we mention the two patterns observed in severe COVID-19 (i.e. interleukin-1β-driven macrophage activation syndrome vs. interleukin-6-driven immune dysregulation). Next, reviewing current evidence drawn from clinical trials, we examine a number of cytokine and anti-cytokine therapies, including interleukin-1, -6, and TNF inhibitors, as well as less targeted therapies, such as corticosteroids, chloroquine, or JAK inhibitors.

Can we use interleukin-6 (IL-6) blockade for coronavirus disease 2019 (COVID-19)-induced cytokine release syndrome (CRS)?

The emergent outbreak of coronavirus disease 2019 (COVID-19) has caused a global pandemic. Acute respiratory distress syndrome (ARDS) and multiorgan dysfunction are among the leading causes of death in critically ill patients with COVID-19. The elevated inflammatory cytokines suggest that a cytokine storm, also known as cytokine release syndrome (CRS), may play a major role in the pathology of COVID-19. However, the efficacy of corticosteroids, commonly utilized antiinflammatory agents, to treat COVID-19-induced CRS is controversial. There is an urgent need for novel therapies to treat COVID-19-induced CRS. Here, we discuss the pathogenesis of severe acute respiratory syndrome (SARS)-induced CRS, compare the CRS in COVID-19 with that in SARS and Middle East respiratory syndrome (MERS), and summarize the existing therapies for CRS. We propose to utilize interleukin-6 (IL-6) blockade to manage COVID-19-induced CRS and discuss several factors that should be taken into consideration for its clinical application.

Weathering the Cytokine Storm in COVID-19: Therapeutic Implications

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) recently emerged in Wuhan, Hubei-China, as responsible for the coronavirus disease 2019 (COVID-19) and then spread rapidly worldwide. While most individuals remain asymptomatic or develop only mild symptoms, approximately 5% develop severe forms of COVID-19 characterized by acute respiratory distress syndrome (ARDS) and multiple-organ failure (MOF) that usually require intensive-care support and often yield a poor prognosis.

SUMMARY

The pathophysiology of COVID-19 is far from being completely understood, and the lack of effective treatments leads to a sense of urgency to develop new therapeutic strategies based on pathophysiological assumptions. The exaggerated cytokine release in response to viral infection, a condition known as cytokine release syndrome (CRS) or cytokine storm, is emerging as the mechanism leading to ARDS and MOF in COVID-19, thus endorsing the hypothesis that properly timed anti-inflammatory therapeutic strategies could improve patients' clinical outcomes and prognosis. Key Messages: The objective of this article is to explore and comment on the potential role of the promising immunomodulatory therapies using pharmacological and nonpharmacological approaches to overcome the dysregulated proinflammatory response in COVID-19.

Should we stimulate or suppress immune responses in COVID-19? Cytokine and anti-cytokine interventions

The coronavirus disease-19 pandemic (COVID-19), which appeared in China in December 2019 and rapidly spread throughout the world, has forced clinicians and scientists to take up extraordinary challenges. This unprecedented situation led to the inception of numerous fundamental research protocols and many clinical trials. It quickly became apparent that although COVID-19, in the vast majority of cases, was a benign disease, it could also develop a severe form with sometimes fatal outcomes. Cytokines are central to the pathophysiology of COVID-19; while some of them are beneficial (type-I interferon, interleukin-7), others appear detrimental (interleukin-1β, -6, and TNF-α) particularly in the context of the so-called cytokine storm. Yet another characteristic of the disease has emerged: concomitant immunodeficiency, notably involving impaired type-I interferon response, and lymphopenia. This review provides an overview of current knowledge on COVID-19 immunopathology. We discuss the defective type-I IFN response, the theoretical role of IL-7 to restore lymphocyte repertoire, as well as we mention the two patterns observed in severe COVID-19 (i.e. interleukin-1β-driven macrophage activation syndrome vs. interleukin-6-driven immune dysregulation). Next, reviewing current evidence drawn from clinical trials, we examine a number of cytokine and anti-cytokine therapies, including interleukin-1, -6, and TNF inhibitors, as well as less targeted therapies, such as corticosteroids, chloroquine, or JAK inhibitors.

Hemophagocytic lymphohistiocytosis: An update on pathogenesis, diagnosis, and therapy

Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening state of immune hyperactivation that arises in the setting of genetic mutations and infectious, inflammatory, or neoplastic triggers. Sustained, aberrant activation of cytotoxic CD8⁺ T cells and resultant inflammatory cytokine release are core pathogenic mechanisms. Key clinical features include high persistent fever, hepatosplenomegaly, blood cytopenia, elevated aminotransferase and ferritin levels, and coagulopathy. HLH is likely under-recognized, and mortality remains high, especially in adults; thus, prompt diagnosis and treatment are essential. Familial forms of HLH are currently treated with chemotherapy as a bridge to hematopoietic stem cell transplantation. HLH occurring in rheumatic disease (macrophage activation syndrome) is treated with glucocorticoids, IL-1 blockade, or cyclosporine A. In other forms of HLH, addressing the underlying trigger is essential. There remains a pressing need for more sensitive, context-specific diagnostic tools. Safer, more effective therapies will arise with improved understanding of the cellular and molecular mechanisms of HLH.

The Society for Immunotherapy of Cancer perspective on regulation of interleukin-6 signaling in COVID-19-related systemic inflammatory response

The pandemic caused by the novel coronavirus SARS-CoV-2 has placed an unprecedented burden on healthcare systems around the world. In patients who experience severe disease, acute respiratory distress is often accompanied by a pathological immune reaction, sometimes referred to as 'cytokine storm'. One hallmark feature of the profound inflammatory state seen in patients with COVID-19 who succumb to pneumonia and hypoxia is marked elevation of serum cytokines, especially interferon gamma, tumor necrosis factor alpha, interleukin 17 (IL-17), interleukin 8 (IL-8) and interleukin 6 (IL-6). Initial experience from the outbreaks in Italy, China and the USA has anecdotally demonstrated improved outcomes for critically ill patients with COVID-19 with the administration of cytokine-modulatory therapies, especially anti-IL-6 agents. Although ongoing trials are investigating anti-IL-6 therapies, access to these therapies is a concern, especially as the numbers of cases worldwide continue to climb. An immunology-informed approach may help identify alternative agents to modulate the pathological inflammation seen in patients with COVID-19. Drawing on extensive experience administering these and other immune-modulating therapies, the Society for Immunotherapy of Cancer offers this perspective on potential alternatives to anti-IL-6 that may also warrant consideration for management of the systemic inflammatory response and pulmonary compromise that can be seen in patients with severe COVID-19.

Pediatric macrophage activation syndrome, recognizing the tip of the Iceberg

Macrophage activation syndrome (MAS) is the name given to secondary hemophagocytic lymphohistiocytosis (sHLH) associated with rheumatic diseases. Previously, MAS has been best studied in children with systemic juvenile idiopathic arthritis (sJIA), who are at high risk of developing MAS. MAS/sHLH is a cytokine storm that results in multi-organ system failure and is frequently fatal. Early diagnosis and treatment is critical for improving survival. Various diagnostic tools have been developed for identifying MAS in the setting of sJIA, as well as for all forms of MAS/sHLH. These are largely based on clinical (e.g., fever) and laboratory features (e.g., cytopenias). None are perfectly sensitive and specific, however, increasing awareness of this condition is also paramount in making the diagnosis. Rare familial forms of HLH can also be diagnosed based on homozygous mutation in genes largely involved in perforin-mediated cytolytic function of lymphocytes (natural killer cells and CD8 T cells). Intriguingly, heterozygous defects in these same genes are frequently identified in patients with sHLH and MAS. Decreased cytolytic function results in prolonged interaction of the lytic lymphocytes and their target antigen presenting cells, thus resulting in the pro-inflammatory cytokine storm believed responsible for the multi-organ failure. Novel cytokine-targeted therapies are currently being explored for a less toxic yet effective alternative to chemotherapeutic approaches to treating children with sHLH/MAS. As increased recognition and diagnosis of MAS is on the rise, an earlier and cytokine-targeted approach to therapy will likely save many lives of children with this disorder.

The Immunology of Macrophage Activation Syndrome

Synonymous with secondary hemophagocytic lymphohistiocytosis, macrophage activation syndrome (MAS) is a term used by rheumatologists to describe a potentially life-threatening complication of systemic inflammatory disorders, most commonly systemic juvenile idiopathic arthritis (sJIA) and systemic lupus erythematosus (SLE). Clinical and laboratory features of MAS include sustained fever, hyperferritinemia, pancytopenia, fibrinolytic coagulopathy, and liver dysfunction. Soluble interleukin-2 receptor alpha chain (sCD25) and sCD163 may be elevated, and histopathology often reveals characteristic increased hemophagocytic activity in the bone marrow (and other tissues), with positive CD163 (histiocyte) staining. A common hypothesis as to the pathophysiology of many cases of MAS proposes a defect in lymphocyte cytolytic activity. Specific heterozygous gene mutations in familial HLH-associated cytolytic pathway genes (e.g., PRF1, UNC13D) have been linked to a substantial subset of MAS patients. In addition, the pro-inflammatory cytokine environment, particularly IL-6, has been shown to decrease NK cell cytolytic function. The inability of NK cells and cytolytic CD8 T cells to lyse infected and otherwise activated antigen presenting cells results in prolonged cell-to-cell (innate and adaptive immune cells) interactions and amplification of a pro-inflammatory cytokine cascade. The cytokine storm results in activation of macrophages, causing hemophagocytosis, as well as contributing to multi-organ dysfunction. In addition to macrophages, dendritic cells likely play a critical role in antigen presentation to cytolytic lymphocytes, as well as contributing to cytokine expression. Several cytokines, including tumor necrosis factor, interferon-gamma, and numerous interleukins (i.e., IL-1, IL-6, IL-18, IL-33), have been implicated in the cytokine cascade. In addition to broadly immunosuppressive therapies, novel cytokine targeted treatments are being explored to dampen the overly active immune response that is responsible for much of the pathology seen in MAS.

Cytokine release syndrome: grading, modeling, and new therapy

Genetically modified T cells that express a chimeric antigen receptor (CAR) are opening a new frontier in cancer immunotherapy. CAR T cells currently are in clinical trials for many cancer types. Cytokine release syndrome (CRS) and neurotoxicities (CAR-related encephalopathy syndrome, CRES) are major adverse events limiting wide deployment of the CAR T cell treatment. Major efforts are ongoing to characterize the pathogenesis and etiology of CRS and CRES. Mouse models have been established to facilitate the study of pathogenesis of the major toxicities of CAR T cells. Myeloid cells including macrophages and monocytes, not the CAR T cells, were found to be the major cells mediating CRS and CRES by releasing IL-1 and IL-6 among other cytokines. Blocking IL-1 or depletion of monocytes abolished both CRS and CRES, whereas IL-6 blocker can ameliorate CRS but not CRES. Therefore, both IL-1 and IL-6 are major cytokines for CRS, though IL-1 is responsible for CRES. It was also demonstrated in the mouse models that blocking CRS does not interfere with the CAR T cell antitumor functions. We summarized new developments in the grading, modeling, and possible new therapeutic approaches for CRS and CRES in this review.

Overcoming barriers of car T-cell therapy in patients with mesothelin-expressing cancers

One obstacle to the application of immunotherapy to solid malignancies is to overcome the existing tolerance to self-antigens. Vaccine strategies aimed at harnessing endogenous antitumor T cells are limited by the T-cell receptor repertoire, which can be detected within the thymus as central tolerance or rendered nonfunctional by post-thymic mechanisms of peripheral tolerance. Adoptive immunotherapy can overcome these obstacles, since therapeutically effective T cells can be engineered to recognize tumors. Continued advancements in novel treatments, including immunotherapy, in solid malignancies are imperative. While mesothelin is an attractive target for cancer immunotherapy given its normal expression is limited to mesothelial cells, the breakthrough for chimeric antigen receptor T-cell treatment against this antigen is still forthcoming.

Current concepts in the diagnosis and management of cytokine release syndrome

As immune-based therapies for cancer become potent, more effective, and more widely available, optimal management of their unique toxicities becomes increasingly important. Cytokine release syndrome (CRS) is a potentially life-threatening toxicity that has been observed following administration of natural and bispecific antibodies and, more recently, following adoptive T-cell therapies for cancer. CRS is associated with elevated circulating levels of several cytokines including interleukin (IL)-6 and interferon γ, and uncontrolled studies demonstrate that immunosuppression using tocilizumab, an anti-IL-6 receptor antibody, with or without corticosteroids, can reverse the syndrome. However, because early and aggressive immunosuppression could limit the efficacy of the immunotherapy, current approaches seek to limit administration of immunosuppressive therapy to patients at risk for life-threatening consequences of the syndrome. This report presents a novel system to grade the severity of CRS in individual patients and a treatment algorithm for management of CRS based on severity. The goal of our approach is to maximize the chance for therapeutic benefit from the immunotherapy while minimizing the risk for life threatening complications of CRS.

The inflammatory twitch as a general strategy for controlling the host response

Allergic inflammation is a general host-defense mechanism for dealing with perceived foreign invaders. Although most effort has been directed toward understanding how this response gets turned on, how it gets turned off again when no longer needed is just as important to an organism's survival. We postulate that the control of the allergic inflammatory response is achieved via frequency modulation whereby a sequence of self-resolving events is repetitively invoked only so long as Ag is present. This leads to the notion of a unitary inflammatory event that we argue has formal similarity to the skeletal muscle twitch, albeit manifest over a much longer time scale. To test the plausibility of this hypothesis, we created an agent-based computational model of the allergic inflammatory response in the lungs. Continual stimulation of the model results in cycles of tissue damage and repair interspersed with periods of nonresponsiveness indicative of a refractory period. These findings are consistent with the inflammatory twitch hypothesis and the notion that the allergic inflammatory response is controlled via frequency modulation. We speculate that chronic inflammatory diseases may represent a failure of the inflammatory twitch to resolve toward baseline.