COVID-19 disease, caused by SARS-CoV-2 infection, has resulted in more than 15.5 million infections and 634,000 deaths worldwide. A recent study of hospitals in New York City, at the initial epicenter of the COVID-19 pandemic in the United States, reported that, during March 2020, 21% of patients hospitalized with confirmed COVID-19 died 1 . These findings are aligned with outcomes observed in the Mount Sinai Health System 2,3 . There are currently no curative or preventive therapies for COVID-19, highlighting the need to enhance current understanding of SARS-CoV-2 pathogenesis for the rational development of therapeutics.Recent studies have suggested that, in addition to direct viral damage, uncontrolled inflammation contributes to disease severity in 5 ). Consistent with this hypothesis, high levels of inflammatory markers, including C-reactive protein (CRP), ferritin and D-dimer, high neutrophil-to-lymphocyte ratio [6][7][8][9] and increased levels of inflammatory cytokines and chemokines 6,8-11 have been observed in patients with severe diseases. Pathogenic inflammation, also referred to as cytokine storm, shares similarities with what was previously seen in patients infected with other severe coronaviruses, including SARS-CoV and Middle East respiratory syndrome coronavirus 12 , and bears similarities to cytokine release syndrome (CRS) observed in patients with cancer treated with chimeric antigen receptor-modified (CAR) T cells 13 . Tocilizumab, an IL-6 receptor inhibitor, is a US Food and Drug Administration (FDA)-approved treatment for CRS in patients receiving CAR T cells 14 . Several single-center studies have used IL-6 inhibitors to treat patients with COVID-19 with some clinical benefits 15 and reported failures 14 . Beyond IL-6, several cytokines have been shown to be elevated in CRS and to contribute to tissue damage. TNF-α is important in nearly all acute inflammatory reactions, acting as an amplifier of inflammation. TNF-α blockade has been used to treat more than ten different autoimmune inflammatory diseases, suggesting that this might be a potential therapeutic approach to reduce organ damage in patients with ). IL-1 is also a highly active pro-inflammatory cytokine, and monotherapy blocking

Initially, children were thought to be spared from disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, a month into the epidemic, a novel multisystem inflammatory syndrome in children (MIS-C) emerged. Herein, we report on the immune profiles of nine MIS-C cases. All MIS-C patients had evidence of prior SARS-CoV-2 exposure, mounting an antibody response with intact neutralization capability. Cytokine profiling identified elevated signatures of inflammation (IL-18 and IL-6), lymphocytic and myeloid chemotaxis and activation (CCL3, CCL4, and CDCP1) and mucosal immune dysregulation (IL-17A, CCL20, CCL28). Immunophenotyping of peripheral blood revealed reductions of non-classical monocytes, and subsets of NK- and T- lymphocytes, suggesting extravasation to affected tissues. Finally, we profiled the auto-antigen reactivity of MIS-C plasma, which revealed both known disease-associated autoantibodies (anti-La) and novel candidates that recognize endothelial, gastrointestinal and immune-cell antigens. All patients were treated with anti-IL6R antibody and/or IVIG, which led to rapid disease resolution.

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Melanoma patients present with elevated levels of Tregs, Ts, and MDSC within established tumors. Direct injection of Oncovex(GM-CSF) induces local and systemic antigen-specific T cell responses and decreases Treg, Ts, and MDSC in patients exhibiting therapeutic responses.

Endothelial cells have been shown to activate T cell responses to alloantigens, triggering transplant rejection. However, they may also play a role in tolerance induction. Using RT-PCR we show here that alloantigen specific CD8(+)CD28(-) T suppressor cells generated in vitro are FOXP3 positive and interact with human endothelial cells. This interaction results in the induction of inhibitory receptors and down-regulation of costimulatory and adhesion molecules, thus rendering endothelial cells tolerogenic. In turn, tolerized endothelial cells elicit the differentiation of CD8(+)CD28(-) FOXP3(+) T suppressor cells. Taken together our data demonstrate a functional and phenotypic overlap between tolerogenic dendritic cells and endothelial cells. Furthermore, alloantigen specific CD8(+)CD28(-) FOXP3(+) T cells, which trigger the upregulation of inhibitory receptors in endothelial cells, are present in the circulation of heart allograft recipients in quiescence as demonstrated by flow cytometry, RT-PCR and luciferase transcription assays. Their detection facilitates the identification of patients who may benefit from partial or complete cessation of immunosuppressive therapy, a goal of obvious importance given the morbidity and mortality associated with chronic immunosuppression. Modulation of endothelial cells in favor of promoting tolerance may be important for long-term survival of organ allografts.

The number of Tregs, defined as CD4+CD25(hi) T cells is increased in patients with MM and RCC. High-dose IL-2 resulted in a significant decrease of Tregs in those patients achieving an objective clinical response to IL-2 therapy.

To identify factors that regulate gut microbiota density and the impact of varied microbiota density on health, we assayed this fundamental ecosystem property in fecal samples across mammals, human disease, and therapeutic interventions. Physiologic features of the host (carrying capacity) and the fitness of the gut microbiota shape microbiota density. Therapeutic manipulation of microbiota density in mice altered host metabolic and immune homeostasis. In humans, gut microbiota density was reduced in Crohn’s disease, ulcerative colitis, and ileal pouch-anal anastomosis. The gut microbiota in recurrent Clostridium difficile infection had lower density and reduced fitness that were restored by fecal microbiota transplantation. Understanding the interplay between microbiota and disease in terms of microbiota density, host carrying capacity, and microbiota fitness provide new insights into microbiome structure and microbiome targeted therapeutics.Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).

A subset of patients with depression have elevated levels of inflammatory cytokines, and some studies demonstrate interaction between inflammatory factors and treatment outcome. However, most studies focus on only a narrow subset of factors in a patient sample. In the current study, we analyzed broad immune profiles in blood from patients with treatment-resistant depression (TRD) at baseline and following treatment with the glutamate modulator ketamine. Serum was analyzed from 26 healthy control and 33 actively depressed TRD patients free of antidepressant medication, and matched for age, sex and body mass index. All subjects provided baseline blood samples, and TRD subjects had additional blood draw at 4 and 24 h following intravenous infusion of ketamine (0.5 mg kg−1). Samples underwent multiplex analysis of 41 cytokines, chemokines and growth factors using quantitative immunoassay technology. Our a priori hypothesis was that TRD patients would show elevations in canonical pro-inflammatory cytokines; analyses demonstrated significant elevation of the pro-inflammatory cytokine interleukin-6. Further exploratory analyses revealed significant regulation of four additional soluble factors in patients with TRD. Several cytokines showed transient changes in level after ketamine, but none correlated with treatment response. Low pretreatment levels of fibroblast growth factor 2 were associated with ketamine treatment response. In sum, we found that patients with TRD demonstrate a unique pattern of increased inflammatory mediators, chemokines and colony-stimulating factors, providing support for the immune hypothesis of TRD. These patterns suggest novel treatment targets for the subset of patients with TRD who evidence dysregulated immune functioning.