Single-cell multi-omics analysis of the immune response in COVID-19.

Analysis of human blood immune cells provides insights into the coordinated response to viral infections such as severe acute respiratory syndrome coronavirus 2, which causes coronavirus disease 2019 (COVID-19). We performed single-cell transcriptome, surface proteome and T and B lymphocyte antigen receptor analyses of over 780,000 peripheral blood mononuclear cells from a cross-sectional cohort of 130 patients with varying severities of COVID-19. We identified expansion of nonclassical monocytes expressing complement transcripts (CD16+C1QA/B/C+) that sequester platelets and were predicted to replenish the alveolar macrophage pool in COVID-19. Early, uncommitted CD34+ hematopoietic stem/progenitor cells were primed toward megakaryopoiesis, accompanied by expanded megakaryocyte-committed progenitors and increased platelet activation. Clonally expanded CD8+ T cells and an increased ratio of CD8+ effector T cells to effector memory T cells characterized severe disease, while circulating follicular helper T cells accompanied mild disease. We observed a relative loss of IgA2 in symptomatic disease despite an overall expansion of plasmablasts and plasma cells. Our study highlights the coordinated immune response that contributes to COVID-19 pathogenesis and reveals discrete cellular components that can be targeted for therapy.

Defining the Skin Cellular Community Using Single-Cell Genomics to Advance Precision Medicine.

Single-cell genomics has revolutionized biological science, enabling high-resolution analysis of human tissues. The ability to demonstrate the role and function of distinct cell types comprising human tissues paves the way for a new understanding of cellular pathways, interactions, and future research directions. The skin, easily accessible and possessing a diverse and complex role in defending us both physically and immunologically from the outside world, lends itself ideally to single-cell genomics analysis. Here, we outline the benefits of single-cell RNA sequencing while also highlighting the challenges in achieving a meaningful result from its use. Key milestones relating to the study of skin in this way are introduced, covering both healthy and diseased states, and we discuss the potential promise of single-cell RNA sequencing to result in tangible medical advances, with a particular focus on precision medicine.

Toxic epidermal necrolysis occurring with immune checkpoint inhibitors.

Nivolumab and ipilimumab are immune checkpoint inhibitors (ICIs) used in the management of advanced malignancies including malignant melanoma. Although several cutaneous adverse events have been reported with these immunotherapy agents, toxic epidermal necrolysis (TEN) secondary to ICIs is rare. We report a 67-year-old man with TEN occurring during nivolumab and ipilimumab co-therapy and review published cases to highlight the challenges in recognizing and managing these patients. ICI-induced TEN can present atypically with delayed onset in comorbid, immunosuppressed patients with an associated high mortality rate. Prompt recognition and drug withdrawal are essential to improve outcomes. High dose systemic corticosteroid has also been recommended for the management of ICI-induced TEN, unlike other drug-induced TEN for which optimal immunomodulatory treatment is still debated.