Summary Background Since December, 2019, Wuhan, China, has experienced an outbreak of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Epidemiological and clinical characteristics of patients with COVID-19 have been reported but risk factors for mortality and a detailed clinical course of illness, including viral shedding, have not been well described. Methods In this retrospective, multicentre cohort study, we included all adult inpatients (≥18 years old) with laboratory-confirmed COVID-19 from Jinyintan Hospital and Wuhan Pulmonary Hospital (Wuhan, China) who had been discharged or had died by Jan 31, 2020. Demographic, clinical, treatment, and laboratory data, including serial samples for viral RNA detection, were extracted from electronic medical records and compared between survivors and non-survivors. We used univariable and multivariable logistic regression methods to explore the risk factors associated with in-hospital death. Findings 191 patients (135 from Jinyintan Hospital and 56 from Wuhan Pulmonary Hospital) were included in this study, of whom 137 were discharged and 54 died in hospital. 91 (48%) patients had a comorbidity, with hypertension being the most common (58 [30%] patients), followed by diabetes (36 [19%] patients) and coronary heart disease (15 [8%] patients). Multivariable regression showed increasing odds of in-hospital death associated with older age (odds ratio 1·10, 95% CI 1·03–1·17, per year increase; p=0·0043), higher Sequential Organ Failure Assessment (SOFA) score (5·65, 2·61–12·23; p Interpretation The potential risk factors of older age, high SOFA score, and d-dimer greater than 1 μg/mL could help clinicians to identify patients with poor prognosis at an early stage. Prolonged viral shedding provides the rationale for a strategy of isolation of infected patients and optimal antiviral interventions in the future. Funding Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences; National Science Grant for Distinguished Young Scholars; National Key Research and Development Program of China; The Beijing Science and Technology Project; and Major Projects of National Science and Technology on New Drug Creation and Development.

Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study

The novel coronavirus severe acute respiratory syndrome coronavirus 2 causing the Coronavirus disease (COVID-19) pandemic has ravaged the world with over 72 million total cases and over 1.6 million deaths worldwide as of early December 2020. An overwhelming preponderance of cases and deaths is observed within the elderly population, and especially in those with pre-existing conditions and comorbidities. Aging causes numerous biological changes in the immune system, which are linked to age-related illnesses and susceptibility to infectious diseases. Age-related changes influence the host immune response and therefore not only weaken the ability to fight respiratory infections but also to mount effective responses to vaccines. Immunosenescence and inflamm-aging are considered key features of the aging immune system wherein accumulation of senescent immune cells contribute to its decline and simultaneously increased inflammatory phenotypes cause immune dysfunction. Age-related quantitative and qualitative changes in the immune system affect cells and soluble mediators of both the innate and adaptive immune responses within lymphoid and non-lymphoid peripheral tissues. These changes determine not only the susceptibility to infections, but also disease progression and clinical outcomes thereafter. Furthermore, the response to therapeutics and the immune response to vaccines are influenced by age-related changes within the immune system. Therefore, better understanding of the pathophysiology of aging and the immune response will not only help understand age-related diseases but also guide targeted management strategies for deadly infectious diseases like COVID-19.

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Aging, Immunity, and COVID-19: How Age Influences the Host Immune Response to Coronavirus Infections?

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus (SARS-CoV)-2, continues to cause substantial morbidity and mortality. While most infections are mild, some patients experience severe and potentially fatal systemic inflammation, tissue damage, cytokine storm and acute respiratory distress syndrome. The innate immune system acts as the first line of defense, sensing the virus through pattern recognition receptors and activating inflammatory pathways that promote viral clearance. Here, we discuss innate immune processes involved in SARS-CoV-2 recognition and the resultant inflammation. Improved understanding of how the innate immune system detects and responds to SARS-CoV-2 will help identify targeted therapeutic modalities that mitigate severe disease and improve patient outcomes. Kanneganti and Diamond review the key role played by innate immunity in the control and immunopathology of COVID-19. 

/pdf/innate-immunity-the-first-line-of-defense-against-sars-cov-2-1i8cd51k.pdf

Innate immunity: the first line of defense against SARS-CoV-2

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), results in life-threatening disease in a minority of patients, especially elderly people and those with co-morbidities such as obesity and diabetes. Severe disease is characterized by dysregulated cytokine release, pneumonia and acute lung injury, which can rapidly progress to acute respiratory distress syndrome, disseminated intravascular coagulation, multisystem failure and death. However, a mechanistic understanding of COVID-19 progression remains unclear. Here we review evidence that SARS-CoV-2 directly or indirectly activates inflammasomes, which are large multiprotein assemblies that are broadly responsive to pathogen-associated and stress-associated cellular insults, leading to secretion of the pleiotropic IL-1 family cytokines (IL-1β and IL-18), and pyroptosis, an inflammatory form of cell death. We further discuss potential mechanisms of inflammasome activation and clinical efforts currently under way to suppress inflammation to prevent or ameliorate severe COVID-19.

/pdf/inflammasome-activation-at-the-crux-of-severe-covid-19-4olietu0hi.pdf

Inflammasome activation at the crux of severe COVID-19.

Since the initial report of the novel Coronavirus Disease 2019 (COVID-19) emanating from Wuhan, China, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has spread globally. While the effects of SARS-CoV-2 infection are not completely understood, there appears to be a wide spectrum of disease ranging from mild symptoms to severe respiratory distress, hospitalization, and mortality. There are no Food and Drug Administration (FDA)-approved treatments for COVID-19 aside from remdesivir; early efforts to identify efficacious therapeutics for COVID-19 have mainly focused on drug repurposing screens to identify compounds with antiviral activity against SARS-CoV-2 in cellular infection systems. These screens have yielded intriguing hits, but the use of nonhuman immortalized cell lines derived from non-pulmonary or gastrointestinal origins poses any number of questions in predicting the physiological and pathological relevance of these potential interventions. While our knowledge of this novel virus continues to evolve, our current understanding of the key molecular and cellular interactions involved in SARS-CoV-2 infection is discussed in order to provide a framework for developing the most appropriate in vitro toolbox to support current and future drug discovery efforts.

/pdf/sars-cov-2-tropism-entry-replication-and-propagation-1az1zoes19.pdf

SARS-CoV-2 tropism, entry, replication, and propagation: Considerations for drug discovery and development.

Coronaviruses: Innate Immunity, Inflammasome Activation, Inflammatory Cell Death, and Cytokines.

Inflammasomes are important sentinels of innate immune defence, sensing pathogens and inducing cell death in infected cells1. There are several inflammasome sensors that each detect and respond to a specific pathogen- or damage-associated molecular pattern (PAMP or DAMP, respectively)1. During infection, live pathogens can induce the release of multiple PAMPs and DAMPs, which can simultaneously engage multiple inflammasome sensors2–5. Here we found that AIM2 regulates the innate immune sensors pyrin and ZBP1 to drive inflammatory signalling and a form of inflammatory cell death known as PANoptosis, and provide host protection during infections with herpes simplex virus 1 and Francisella novicida. We also observed that AIM2, pyrin and ZBP1 were members of a large multi-protein complex along with ASC, caspase-1, caspase-8, RIPK3, RIPK1 and FADD, that drove inflammatory cell death (PANoptosis). Collectively, our findings define a previously unknown regulatory and molecular interaction between AIM2, pyrin and ZBP1 that drives assembly of an AIM2-mediated multi-protein complex that we term the AIM2 PANoptosome and comprising multiple inflammasome sensors and cell death regulators. These results advance the understanding of the functions of these molecules in innate immunity and inflammatory cell death, suggesting new therapeutic targets for AIM2-, ZBP1- and pyrin-mediated diseases. AIM2 responds to infection with herpes simplex virus 1 or Francisella novicida by driving assembly of a large multi-protein complex containing multiple inflammasome sensors and cell death regulators.

AIM2 forms a complex with pyrin and ZBP1 to drive PANoptosis and host defence

ADAR1 restricts ZBP1-mediated immune response and PANoptosis to promote tumorigenesis.

PANoptosis in microbial infection.

Resistance to cell death is a hallmark of cancer. Immunotherapy, particularly immune checkpoint blockade therapy, drives immune-mediated cell death and has greatly improved treatment outcomes for some patients with cancer, but it often fails clinically. Its success relies on the cytokines and cytotoxic functions of effector immune cells to bypass the resistance to cell death and eliminate cancer cells. However, the specific cytokines capable of inducing cell death in tumors and the mechanisms that connect cytokines to cell death across cancer cell types remain unknown. In this study, we analyzed expression of several cytokines that are modulated in tumors and found correlations between cytokine expression and mortality. Of several cytokines tested for their ability to kill cancer cells, only TNF-α and IFN-γ together were able to induce cell death in 13 distinct human cancer cell lines derived from colon and lung cancer, melanoma, and leukemia. Further evaluation of the specific programmed cell death pathways activated by TNF-α and IFN-γ in these cancer lines identified PANoptosis, a form of inflammatory cell death that was previously shown to be activated by contemporaneous engagement of components from pyroptosis, apoptosis, and/or necroptosis. Specifically, TNF-α and IFN-γ triggered activation of gasdermin D, gasdermin E, caspase-8, caspase-3, caspase-7, and MLKL. Furthermore, the intratumoral administration of TNF-α and IFN-γ suppressed the growth of transplanted xenograft tumors in an NSG mouse model. Overall, this study shows that PANoptosis, induced by synergism of TNF-α and IFN-γ, is an important mechanism to kill cancer cells and suppress tumor growth that could be therapeutically targeted.

https://www.immunohorizons.org/content/immunohorizon/5/7/568.full.pdf

SangJoon Lee

Papers

Coronaviruses: Innate Immunity, Inflammasome Activation, Inflammatory Cell Death, and Cytokines.

AIM2 forms a complex with pyrin and ZBP1 to drive PANoptosis and host defence

ADAR1 restricts ZBP1-mediated immune response and PANoptosis to promote tumorigenesis.

PANoptosis in microbial infection.

Inflammatory Cell Death, PANoptosis, Mediated by Cytokines in Diverse Cancer Lineages Inhibits Tumor Growth.