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In early 2020, at first surge of the coronavirus disease 2019 (COVID-19) pandemic, many health care workers (HCW) were re-deployed to critical care environments to support intensive care teams looking after patients with severe COVID-19. There was considerable anxiety of increased risk of COVID-19 for these staff. To determine whether critical care HCW were at increased risk of hospital acquired infection, we explored the relationship between workplace, patient facing role and evidence of immune exposure to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within a quaternary hospital providing a regional critical care response. Routine viral surveillance was not available at this time.

Background: Patients with autoimmune/inflammatory conditions on anti- CD20 therapies, such as rituximab, have suboptimal humoral responses to vaccination and are vulnerable to poorer clinical outcomes following SARSCoV-2 infection. We aimed to examine how the fundamental parameters of antibody responses, namely, affinity and concentration, shape the quality of humoral immunity after vaccination in these patients. Methods: We performed in-depth antibody characterisation in sera collected 4 to 6 weeks after each of three vaccine doses to wild-type (WT) SARS-CoV- 2 in rituximab-treated primary vasculitis patients (n = 14) using Luminex and pseudovirus neutralisation assays, whereas we used a novel microfluidicbased immunoassay to quantify polyclonal antibody affinity and concentration against both WT and Omicron (B.1.1.529) variants. We performed comparative antibody profiling at equivalent timepoints in healthy individuals after three antigenic exposures to WT SARS-CoV-2 (one infection and two vaccinations; n = 15) and in convalescent patients after WT SARS-CoV-2 infection (n = 30). Results: Rituximab-treated patients had lower antibody levels and neutralisation titres against both WT and Omicron SARS-CoV-2 variants compared to healthy individuals. Neutralisation capacity was weaker against Omicron versus WT both in rituximab-treated patients and in healthy individuals. In the rituximab cohort, this was driven by lower antibody affinity against Omicron versus WT [median (range) KD: 21.6 (9.7-- 38.8) nM vs. 4.6 (2.3--44.8) nM, p = 0.0004]. By contrast, healthy individuals with hybrid immunity produced a broader antibody response, a subset of which recognised Omicron with higher affinity than antibodies in rituximabtreated patients [median (range) KD: 1.05 (0.45--1.84) nM vs. 20.25 (13.2--38.8) nM, p = 0.0002], underpinning the stronger serum neutralisation capacity against Omicron in the former group. Rituximab-treated patients had similar anti-WT antibody levels and neutralisation titres to unvaccinated convalescent individuals, despite two more exposures to SARS-CoV-2 antigen. Temporal profiling of the antibody response showed evidence of affinity maturation in healthy convalescent patients after a single SARS-CoV- 2 infection, which was not observed in rituximab-treated patients, despite repeated vaccination. Discussion: Our results enrich previous observations of impaired humoral immune responses to SARS-CoV-2 in rituximab-treated patients and highlight the significance of quantitative assessment of serum antibody affinity and concentration in monitoring anti-viral immunity, viral escape, and the evolution of the humoral response. [ABSTRACT FROM AUTHOR]

Objectives: To describe the risk factors for SARS-CoV-2 infection in UK healthcare workers (HCWs).Methods: We conducted a prospective sero-epidemiological study of HCWs at a major UK teaching hospital using a SARS-CoV-2 immunoassay. Risk factors for seropositivity were analysed using multivariate logistic regression.Results: 410/5,698 (7·2%) staff tested positive for SARS-CoV-2 antibodies. Seroprevalence was higher in those working in designated COVID-19 areas compared with other areas (9·47% versus 6·16%) Healthcare assistants (aOR 2·06 [95%CI 1·14-3·71]; p=0·016) and domestic and portering staff (aOR 3·45 [95% CI 1·07-11·42]; p=0·039) had significantly higher seroprevalence than other staff groups after adjusting for age, sex, ethnicity and COVID-19 working location. Staff working in acute medicine and medical sub-specialities were also at higher risk (aOR 2·07 [95% CI 1·31-3·25]; p<0·002). Staff from Black, Asian and minority ethnic (BAME) backgrounds had an aOR of 1·65 (95% CI 1·32 - 2·07; p<0·001) compared to white staff; this increased risk was independent of COVID-19 area working. The only symptoms significantly associated with seropositivity in a multivariable model were loss of sense of taste or smell, fever, and myalgia; 31% of staff testing positive reported no prior symptoms.Conclusions: Risk of SARS-CoV-2 infection amongst HCWs is highly heterogeneous and influenced by COVID-19 working location, role, age and ethnicity. Increased risk amongst BAME staff cannot be accounted for solely by occupational factors. [ABSTRACT FROM AUTHOR]

COVID-19 is associated with neurological complications including stroke, delirium and encephalitis. Furthermore, a post-viral syndrome dominated by neuropsychiatric symptoms is common, and is seemingly unrelated to COVID-19 severity. The true frequency and underlying mechanisms of neurological injury are unknown, but exaggerated host inflammatory responses appear to be a key driver of COVID-19 severity. We investigated the dynamics of, and relationship between, serum markers of brain injury [neurofilament light (NfL), glial fibrillary acidic protein (GFAP) and total tau] and markers of dysregulated host response (autoantibody production and cytokine profiles) in 175 patients admitted with COVID-19 and 45 patients with influenza. During hospitalization, sera from patients with COVID-19 demonstrated elevations of NfL and GFAP in a severity-dependent manner, with evidence of ongoing active brain injury at follow-up 4 months later. These biomarkers were associated with elevations of pro-inflammatory cytokines and the presence of autoantibodies to a large number of different antigens. Autoantibodies were commonly seen against lung surfactant proteins but also brain proteins such as myelin associated glycoprotein. Commensurate findings were seen in the influenza cohort. A distinct process characterized by elevation of serum total tau was seen in patients at follow-up, which appeared to be independent of initial disease severity and was not associated with dysregulated immune responses unlike NfL and GFAP. These results demonstrate that brain injury is a common consequence of both COVID-19 and influenza, and is therefore likely to be a feature of severe viral infection more broadly. The brain injury occurs in the context of dysregulation of both innate and adaptive immune responses, with no single pathogenic mechanism clearly responsible. [ABSTRACT FROM AUTHOR]

Rapid-onset obesity with hypoventilation, hypothalamic dysfunction, autonomic dysregulation, and neural-crest tumour (ROHHAD(NET)) is a rare syndrome presenting in early childhood associated with high morbidity and mortality. There is no specific diagnostic biomarker and diagnosis is based on clinical features. An autoimmune origin has been postulated. Management is largely supportive. We report a case of a five-year old female who presented in respiratory arrest after 6-months of rapid weight gain. She had central hypoventilation, central diabetes insipidus, growth hormone deficiency and hyperprolactinaemia. She displayed elevated interleukin-6 levels on cytokine serology which normalised after rituximab treatment. After rituximab treatment, her weight reduced significantly from greatly above the 99.6th to the 50th centile in 12 months. This response possibly reflects an underlying, immune-inflammatory pathology driving excess adiposity in this condition. Potentially, other aspects of ROHHAD(NET) may be mediated through autoimmune dysregulation in which case rituximab may provide benefits for prognosis and survival. [ABSTRACT FROM AUTHOR]

Selenium, a trace element that is fundamental to human health, is incorporated into some proteins as selenocysteine (Sec), generating a family of selenoproteins. Sec incorporation is mediated by a multiprotein complex that includes Sec insertion sequence--binding protein 2 (SECISBP2; also known as SBP2). Here, we describe subjects with compound heterozygous defects in the SECISBP2 gene. These individuals have reduced synthesis of most of the 25 known human selenoproteins, resulting in a complex phenotype. Azoospermia, with failure of the latter stages of spermatogenesis, was associated with a lack of testis-enriched selenoproteins. An axial muscular dystrophy was also present, with features similar to myopathies caused by mutations in selenoprotein N (SEPN1). Cutaneous deficiencies of antioxidant selenoenzymes, increased cellular ROS, and susceptibility to ultraviolet radiation--induced oxidative damage may mediate the observed photosensitivity. Reduced levels of selenoproteins in peripheral blood cells were associated with impaired T lymphocyte proliferation, abnormal mononuclear cell cytokine secretion, and telomere shortening. Paradoxically, raised ROS in affected subjects was associated with enhanced systemic and cellular insulin sensitivity, similar to findings in mice lacking the antioxidant selenoenzyme glutathione peroxidase 1 (GPx1). Thus, mutation of SECISBP2 is associated with a multisystem disorder with defective biosynthesis of many selenoproteins, highlighting their role in diverse biological processes., Introduction Selenium is an essential trace element that is fundamental to human health. Its biological role is mediated principally by cotranslational incorporation of selenocysteine (Sec; the 21st amino acid) into [...]

Nontyphoidal Salmonellae are a major cause of life-threatening bacteremia among HIV-infected individuals. Although cell-mediated immunity controls intracellular infection, antibodies protect against Salmonella bacteremia. We report that high-titer antibodies specific for Salmonella lipopolysaccharide (LPS) are associated with a Lack of Salmonella-killing in HIV-infected African adults. Killing was restored by genetically shortening LPS from the target Salmonella or removing LPS-specific antibodies from serum. Complement-mediated killing of Salmonella by healthy serum is shown to be induced specifically by antibodies against outer membrane proteins. This killing is Lost when excess antibody against Salmonella LPS is added. Thus, our study indicates that impaired immunity against nontyphoidal Salmonella bacteremia in HIV infection results from excess inhibitory antibodies against Salmonella LPS, whereas serum killing of Salmonella is induced by antibodies against outer membrane proteins. 10.1126/science.1180346

Background: Immune defects in chronic pulmonary aspergillosis (CPA) are poorly characterized. We compared peripheral blood cytokine profiles in patients with CPA versus healthy controls and explored the relationship with disease severity.Methods: Interferon-gamma (IFNγ), interleukin (IL)-17, tumor necrosis factor-α, IL-6, IL-12, and IL-10 were measured after in vitro stimulation of whole blood with lipopolysaccharide (LPS), phytohemagglutinin, β-glucan, zymosan (ZYM), IL-12 or IL-18, and combinations. Clinical parameters and mortality were correlated with cytokine production.Results: Cytokine profiles were evaluated in 133 patients (57.1% male, mean age 61 years). In comparison to controls, patients with CPA had significantly reduced production of IFNγ in response to stimulation with β-glucan + IL-12 (312 vs 988 pg/mL), LPS + IL-12 (252 vs 1033 pg/mL), ZYM + IL-12 (996 vs 2347 pg/mL), and IL-18 + IL-12 (7193 vs 12 330 pg/mL). Age >60 (hazard ratio [HR], 1.71; 95% confidence interval [CI], 1.00-2.91; P = .05) and chronic obstructive pulmonary disease (HR, 1.69; 95% CI, 1.03-2.78; P = .039) were associated with worse survival, whereas high IFNγ production in response to beta-glucan + IL-12 stimulation (HR, 0.48; 95% CI, .25-0.92; P = .026) was associated with reduced mortality.Conclusions: Patients with CPA show impaired IFNγ production in peripheral blood in response to stimuli. Defective IFNγ production ability correlates with worse outcomes. Immunotherapy with IFNγ could be beneficial for patients showing impaired IFNγ production in CPA. [ABSTRACT FROM AUTHOR]

Efforts to define serological correlates of protection against COVID-19 have been hampered by the lack of a simple, scalable, standardised assay for SARS-CoV-2 infection and antibody neutralisation. Plaque assays remain the gold standard, but are impractical for high-throughput screening. In this study, we show that expression of viral proteases may be used to quantitate infected cells. Our assays exploit the cleavage of specific oligopeptide linkers, leading to the activation of cell-based optical biosensors. First, we characterise these biosensors using recombinant SARS-CoV-2 proteases. Next, we confirm their ability to detect viral protease expression during replication of authentic virus. Finally, we generate reporter cells stably expressing an optimised luciferase-based biosensor, enabling viral infection to be measured within 24 h in a 96- or 384-well plate format, including variants of concern. We have therefore developed a luminescent SARS-CoV-2 reporter cell line, and demonstrated its utility for the relative quantitation of infectious virus and titration of neutralising antibodies. Author summary: Techniques for measuring infection with SARS-CoV-2 in the laboratory are laborious and time-consuming, and different laboratories use different approaches. There is therefore no generally agreed way to quantitate neutralising antibodies against SARS-CoV-2, which block infection with the virus and protect people from COVID-19. In this study, we describe a new way to measure SARS-CoV-2 infection, which is much simpler and faster than existing methods. It relies on the production of a specific protease enzyme by the virus, which is able to cleave and activate an engineered protein biosensor in infected cells. This biosensor emits light in the presence of viral infection, and the amount of light released is used as a readout for the amount of infectious SARS-CoV-2 present. The signal is very sensitive, so the number of infected cells required is very small, and the method can be scaled-up to test many samples at once. In particular, we demonstrate how it can be used to detect different variants of SARS-CoV-2, and quantitate neutralising antibodies against these viruses. [ABSTRACT FROM AUTHOR]

Precision monitoring of antibody responses during the COVID-19 pandemic is increasingly important during large scale vaccine rollout and rise in prevalence of Severe Acute Respiratory Syndrome-related Coronavirus-2 (SARS-CoV-2) variants of concern (VOC). Equally important is defining Correlates of Protection (CoP) for SARS-CoV-2 infection and COVID-19 disease. Data from epidemiological studies and vaccine trials identified virus neutralising antibodies (Nab) and SARS-CoV-2 antigen-specific (notably RBD and S) binding antibodies as candidate CoP. In this study, we used the World Health Organisation (WHO) international standard to benchmark neutralising antibody responses and a large panel of binding antibody assays to compare convalescent sera obtained from: a) COVID-19 patients; b) SARS-CoV-2 seropositive healthcare workers (HCW) and c) seronegative HCW. The ultimate aim of this study is to identify biomarkers of humoral immunity that could be used to differentiate severe from mild or asymptomatic SARS-CoV-2 infections. Some of these biomarkers could be used to define CoP in further serological studies using samples from vaccination breakthrough and/or re-infection cases. Whenever suitable, the antibody levels of the samples studied were expressed in International Units (IU) for virus neutralisation assays or in Binding Antibody Units (BAU) for ELISA tests. In this work we used commercial and non-commercial antibody binding assays; a lateral flow test for detection of SARS-CoV-2-specific IgG/IgM; a high throughput multiplexed particle flow cytometry assay for SARS-CoV-2 Spike (S), Nucleocapsid (N) and Receptor Binding Domain (RBD) proteins); a multiplex antigen semi-automated immuno-blotting assay measuring IgM, IgA and IgG; a pseudotyped microneutralisation test (pMN) and an electroporation-dependent neutralisation assay (EDNA). Our results indicate that overall, severe COVID-19 patients showed statistically significantly higher levels of SARS-CoV-2-specific neutralising antibodies (average 1029 IU/ml) than those observed in seropositive HCW with mild or asymptomatic infections (379 IU/ml) and that clinical severity scoring, based on WHO guidelines was tightly correlated with neutralisation and RBD/S antibodies. In addition, there was a positive correlation between severity, N-antibody assays and intracellular virus neutralisation. [ABSTRACT FROM AUTHOR]

The Schnitzler Syndrome (SchS) is an acquired, autoinflammatory condition successfully treated with IL-1 inhibition. The two main defining features of this late-onset condition are neutrophilic urticarial dermatoses (NUD) and the presence of an IgM monoclonal component. While the former aspect has been extensively studied in this disease setting, the enigmatic paraproteinaemia and its potential consequential effects within SchS, has not previously been thoroughly addressed. Previous studies analyzing clonal B cell repertoires have largely focused on autoimmune disorders such as Systemic Lupus Erythematous (SLE) and hematological malignancies such as Chronic Lymphocytic Leukaemia (CLL), where B-cell clonality is central to disease pathology. The present study uses next-generation sequencing to provide detailed insight into aspects of B cell VDJ recombination and properties of the resulting immunoglobulin chains. An overview of IgH regional dynamics in 10 SchS patients, with a particular focus on CDR3 sequences and VDJ gene usage is reported, highlighting the presence of specific B cell expansions. Protein microarray detected a substantial proportion of autoreactive IgM to nuclear target proteins, though a single universal target was not identified. Together, these genetic and functional findings impart new understanding into this rare disorder. [ABSTRACT FROM AUTHOR]

Anti-cytokine autoantibodies may cause immunodeficiency and have been recently recognized as 'autoimmune phenocopies of primary immunodeficiencies' and are found in particular, but not exclusively in adult patients. By blocking the cytokine's biological function, patients with anti-cytokine autoantibodies may present with a similar clinical phenotype as the related inborn genetic disorders. So far, autoantibodies to interferon (IFN)-γ, GM-CSF, to a group of TH-17 cytokines and to IL-6 have been found to be causative or closely associated with susceptibility to infection. This review compares infectious diseases associated with anti-cytokine autoantibodies with primary immunodeficiencies affecting similar cytokines or related pathways. [ABSTRACT FROM AUTHOR]

Background The homozygous K108E mutation of interferon regulatory factor 8 (IRF8) is reported to cause dendritic cell (DC) and monocyte deficiency. However, more widespread immune dysfunction is predicted from the multiple roles ascribed to IRF8 in immune cell development and function. Objective We sought to describe the effect on hematopoiesis and immunity of the compound heterozygous R83C/R291Q mutation of IRF8 , which is present in a patient with recurrent viral infection, granuloproliferation, and intracerebral calcification. Methods Variant IRF8 alleles were identified by means of exome sequencing, and their function was tested by using reporter assays. The cellular phenotype was studied in detail by using flow cytometry, functional immunologic assay transcriptional profiling, and antigen receptor profiling. Results Both mutations affected conserved residues, and R291Q is orthologous to R294, which is mutated in the BXH2 IRF8-deficient mouse. R83C showed reduced nuclear translocation, and neither mutant was able to regulate the Ets/IRF composite element or interferon-stimulated response element, whereas R291Q retained BATF/JUN interactions. DC deficiency and monocytopenia were observed in blood, dermis, and lung lavage fluid. Granulocytes were consistently increased, dysplastic, and hypofunctional. Natural killer cell development and maturation were arrested. T H 1, T H 17, and CD8 + memory T-cell differentiation was significantly reduced, and T cells did not express CXCR3. B-cell development was impaired, with fewer memory cells, reduced class-switching, and lower frequency and complexity of somatic hypermutation. Cell-specific gene expression was widely disturbed in interferon- and IRF8-regulated transcripts. Conclusions This analysis defines the clinical features of human biallelic IRF8 deficiency, revealing a complex immunodeficiency syndrome caused by DC and monocyte deficiency combined with widespread immune dysregulation. [ABSTRACT FROM AUTHOR]

G6PC3 deficiency typically causes severe congenital neutropenia, associated with susceptibility to infections, cardiac and urogenital abnormalities. However, here we describe two boys of Pakistani origin who were found to have G6PC3 deficiency due to c.130 C>T mutation, but who have clinical phenotypes that are typical for a systemic autoinflammatory syndrome. The index case presented with combination of unexplained fevers, severe mucosal ulcers, abdominal symptoms, and inflammatory arthritis. He eventually fully responded to anti-TNF therapy. In this study, we show that compared with healthy controls, neutrophils and monocytes from patients have reduced glycolytic reserve. Considering that healthy myeloid cells have been shown to switch their metabolic pathways to glycolysis in response to inflammatory cues, we studied what impact this might have on production of the inflammatory cytokines. We have demonstrated that patients’ monocytes, in response to lipopolysaccharide, show significantly increased production of IL-1β and IL-18, which is NLRP3 inflammasome dependent. Furthermore, additional whole blood assays have also shown an enhanced production of IL-6 and TNF from the patients’ cells. These cases provide further proof that autoinflammatory complications are also seen within the spectrum of primary immune deficiencies, and resulting from a wider dysregulation of the immune responses. [ABSTRACT FROM AUTHOR]

A child with X-linked osteopetrosis, lymphedema, anhidrotic ectodermal dysplasia, and immunodeficiency (OL-EDA-ID) was recently reported. We report the clinical features of a second boy with this novel syndrome and his mother, who presented with signs of incontinentia pigmenti (IP). The child had mild osteopetrosis without neurosensory complications, unilateral lymphedema of the left leg, and characteristic features of anhidrotic ectodermal dysplasia with sparse hair, facial dysmorphy, delayed eruption of teeth, and sweat gland abnormalities. He died at 18 months of severe immunodeficiency with multiple infections caused by Gram-negative (Salmonella enteritidis) and Gram-positive (Streptococcus pneumoniae) bacteria, nontuberculous mycobacteria (Mycobacterium kansasii), and fungi (Pneumocystis carinii). His 30-year-old mother&apos;s medical history, together with residual cutaneous lesions, was highly suggestive of IP without neurologic impairment. In this patient with OLEDA-ID, we detected the same NF-[kappa]B essential modulator stop codon hypomorphic mutation identified in the previous patient. The occurrence of the same clinical features in 2 unrelated patients with the same genotype demonstrates that OL-EDA-ID is a genuine clinical syndrome. The clinical and biological descriptions of the proband and his mother further corroborate the relationship between IP and EDA. Both syndromes are allelic and are associated with mutations in NF-[kappa]B essential modulator, with a genotype-phenotype correlation in hemizygous males. In contrast, loss-of-function mutations and hypomorphic mutations may cause IP in females. Pediatrics 2002;109(6). URL: http://www. pediatrics.org/cgi/content/full/109/6/e97; children, osteopetrosis, lymphedema, anhidrotic ectodermal dysplasia, incontinentia pigmenti, immunodeficiency, bone marrow transplantation.

Abstract: This review summarizes the association of increased susceptibility to mycobacterial disease in patients with genetic defects affecting innate and adaptive immunity. The optimum function of CD4 T-cell and macrophage function is critically important for immunity against mycobacteria. Antibody, complement and neutrophil function is not required for effective anti-mycobacterial immunity. [Copyright &y& Elsevier]