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.

The past three decades have witnessed remarkable advances in our ability to target specific elements of the immune and inflammatory response, fuelled by advances in both biotechnology and disease knowledge. As well as providing superior treatments for immune-mediated inflammatory diseases (IMIDs), such therapies also offer unrivalled opportunities to study the underlying immunopathological basis of these conditions. In this review, we explore recent approaches to the treatment of IMIDs and the insights to pathobiology that they provide. We review novel biologic agents targeting the T-helper 17 axis, including therapies directed towards interleukin (IL)-17 (secukinumab, ixekizumab, bimekizumab), IL-17R (brodalumab), IL-12/23p40 (ustekinumab, briakinumab) and IL-23p19 (guselkumab, tildrakizumab, brazikumab, risankizumab, mirikizumab). We also present an overview of biologics active against type I and II interferons, including sifalumumab, rontalizumab, anifrolumab and fontolizumab. Emerging strategies to interfere with cellular adhesion processes involved in lymphocyte recruitment are discussed, including both integrin blockade (natalizumab, vedolizumab, etrolizumab) and sphingosine-1-phosphate receptor inhibition (fingolimod, ozanimod). We summarise the development and recent application of Janus kinase (JAK) inhibitors in the treatment of IMIDs, including first-generation pan-JAK inhibitors (tofacitinib, baricitinib, ruxolitinib, peficitinib) and second-generation selective JAK inhibitors (decernotinib, filgotinib, upadacitinib). New biologics targeting B-cells (including ocrelizumab, veltuzumab, tabalumab and atacicept) and the development of novel strategies for regulatory T-cell modulation (including low-dose IL-2 therapy and Tregitopes) are also discussed. Finally, we explore recent biotechnological advances such as the development of bispecific antibodies (ABT-122, COVA322), and their application to the treatment of IMIDs.

Control over postinjury CNS plasticity is a major frontier of science that, if conquered, would open new avenues for treatment of neurological disorders. Here we investigate the functional, physiological, and structural changes in the cerebral cortex associated with chronic deep brain stimulation of the cerebellar output, a treatment approach that has been shown to improve postischemia motor recovery in a rodent model of cortical infarcts. Long–Evans rats were pretrained on the pasta-matrix retrieval task, followed by induction of focal cortical ischemia and implantation of a macroelectrode in the contralesional lateral cerebellar nucleus. Animals were assigned to one of three treatment groups pseudorandomly to balance severity of poststroke motor deficits: REGULAR stimulation, BURST stimulation, or SHAM. Treatment initiated 2 weeks post surgery and continued for 5 weeks. At the end, animals were randomly selected for perilesional intracortical microstimulation mapping and tissue sampling for Western blot analysis or contributed tissue for 3D electron microscopy. Evidence of enhanced cortical plasticity with therapeutically effective stimulation is shown, marked by greater perilesional reorganization in stimulation- treated animals versus SHAM. BURST stimulation was significantly effective for promoting distal forepaw cortical representation. Stimulation-treated animals showed a twofold increase in synaptic density compared with SHAM. In addition, treated animals demonstrated increased expression of synaptic markers of long-term potentiation and plasticity, including synaptophysin, NMDAR1, CaMKII, and PSD95. These findings provide a critical foundation of how deep cerebellar stimulation may guide plastic reparative reorganization after nonprogressive brain injury and indicate strong translational potential.

Many patients with rheumatoid arthritis (RA) achieve disease remission with modern treatment strategies. However, having achieved this state, there are no tests that predict when withdrawal of therapy will result in drug-free remission rather than flare. We aimed to identify predictors of drug-free remission in RA. The Biomarkers of Remission in Rheumatoid Arthritis (BioRRA) Study was a unique, prospective, interventional cohort study of complete and abrupt cessation of conventional synthetic disease-modifying anti-rheumatic drugs (DMARDs). Patients with RA of at least 12 months duration and in clinical and ultrasound remission discontinued DMARDs and were monitored for six months. The primary outcome was time-to-flare, defined as disease activity score in 28 joints with C-reactive protein (DAS28-CRP) ≥ 2.4. Baseline clinical and ultrasound measures, circulating inflammatory biomarkers, and peripheral CD4+ T cell gene expression were assessed for their ability to predict time-to-flare and flare/remission status by Cox regression and receiver-operating characteristic (ROC) analysis respectively. 23/44 (52%) eligible patients experienced an arthritis flare after a median (IQR) of 48 (31.5-86.5) days following DMARD cessation. A composite score incorporating five baseline variables (three transcripts [FAM102B, ENSG00000228010, ENSG00000227070], one cytokine [interleukin-27], one clinical [Boolean remission]) differentiated future flare from drug-free remission with an area under the ROC curve of 0.96 (95% CI 0.91-1.00), sensitivity 0.91 (0.78-1.00) and specificity 0.95 (0.84-1.00). We provide proof-of-concept evidence for predictors of drug-free remission in RA. If validated, these biomarkers could help to personalize immunosuppressant withdrawal: a therapy paradigm shift with ensuing patient and economic benefits.

Background We present the investigation of an outbreak of gastroenteritis at a UK restaurant incorporating both epidemiological and microbiological analysis. Methods Structured postal questionnaires were sent to 30 diners who ate at the restaurant during the outbreak period (5–7 February 2010). Stool specimens collected from staff and diners were submitted for bacterial culture and norovirus testing, and 15 Pacific oysters (Crassostrea gigas) from the batch served during the outbreak period were tested for norovirus. Results A strong association was observed between illness and oyster consumption (odds ratio undefined, confidence interval: 11.7 to infinity, P = 0.00001). Multiple different sequences of norovirus RNA were present in both stool and oyster specimens, typical of a shellfish origin. Several contemporaneous norovirus outbreaks throughout the UK were linked to oysters, particularly, though not exclusively, those sourced from Carlingford Lough in Ireland (as in this study), which were subsequently withdrawn from distribution. Conclusion Despite the risk to human health, there is significant uncertainty surrounding the quantitative correlation between oyster norovirus levels and consumer illness. Continued research should help further our understanding of this crucial correlation and identify ways in which viral depuration of oysters can be enhanced.

Immune-mediated inflammatory diseases (IMIDs) are typically characterised by relapsing and remitting flares of inflammation. However, the unpredictability of disease flares impedes their study. Addressing this critical knowledge gap, we use the experimental medicine approach of immunomodulatory drug withdrawal in rheumatoid arthritis (RA) remission to synchronise flare processes allowing detailed characterisation. Exploratory mass cytometry analyses reveal three circulating cellular subsets heralding the onset of arthritis flare – CD45RO⁺PD1^hi CD4⁺ and CD8⁺ T cells, and CD27⁺CD86⁺CD21^- B cells – further characterised by single-cell sequencing. Distinct lymphocyte subsets including cytotoxic and exhausted CD4⁺ memory T cells, memory CD8⁺CXCR5⁺ T cells, and IGHA1+ plasma cells are primed for activation in flare patients. Regulatory memory CD4⁺ T cells (Treg cells) increase at flare onset, but with dysfunctional regulatory marker expression compared to drug-free remission. Significant clonal expansion is observed in T cells, but not B cells, after drug cessation; this is widespread throughout memory CD8⁺ T cell subsets but limited to the granzyme-expressing cytotoxic subset within CD4⁺ memory T cells. Based on our observations, we suggest a model of immune dysregulation for understanding RA flare, with potential for further translational research towards novel avenues for its treatment and prevention.