Clonal expansion of CD4+CD8+ T cells in an adult patient with Mycoplasma pneumoniae-associated Erythema multiforme majus

Background: Erythema multiforme (EM) is an acute, immune-mediated mucocutaneous disease, most often preceded by herpes simplex virus (HSV) infection or reactivation. Mycoplasma pneumoniae (Mp) is considered the second major trigger of EM and is often associated with an atypical and more severe presentation of disease, characterized by prominent mucosal involvement. However, contrary to HSV-associated Erythema multiforme (HAEM), immunological mechanisms of Mp-associated EM remain unclear. Case presentation: We present the case of a 50-year-old male patient presenting with community-acquired pneumonia (CAP) and erythema multiforme majus (EMM). Acute Mp infection was diagnosed by seroconversion, with no evidence of HSV infection as a cause of EMM. We performed immune phenotyping of blister fluid (BF) and peripheral blood (PB) T cells and detected a clonally expanded TCRV beta 2(+) T cell population that was double positive for CD4 and CD8, and expressed the cytotoxic markers granulysin and perforin. This CD4(+)CD8(+) population comprised up to 50.7% of BF T cells and 24.9% of PB T cells. Two years prior to the onset of disease, the frequency of PB CD4(+)CD8(+)T cells had been within normal range and it gradually returned to baseline levels with the resolution of symptoms, suggesting an involvement of this population in EMM disease pathophysiology. Conclusions: This report is the first to provide a phenotypic description of lesional T cells in Mp-associated EMM. Characterizing the local immune response might help to address pathophysiological questions and warrants further systematic research

NLRP3 protects alveolar barrier integrity by an inflammasome-independent increase of epithelial cell adherence

Bacterial pneumonia is a major cause of acute lung injury and acute respiratory distress syndrome, characterized by alveolar barrier disruption. NLRP3 is best known for its ability to form inflammasomes and to regulate IL- 1β and IL-18 production in myeloid cells. Here we show that NLRP3 protects the integrity of the alveolar barrier in a mouse model of Streptococcus pneumoniae-induced pneumonia, and ex vivo upon treatment of isolated perfused and ventilated lungs with the purified bacterial toxin, pneumolysin. We reveal that the preserving effect of NLRP3 on the lung barrier is independent of inflammasomes, IL-1β and IL-18. NLRP3 improves the integrity of alveolar epithelial cell monolayers by enhancing cellular adherence. Collectively, our study uncovers a novel function of NLRP3 by demonstrating that it protects epithelial barrier function independently of inflammasomes

Differential Role of gp130-Dependent STAT and Ras Signalling for Haematopoiesis Following Bone-Marrow Transplantation

INTRODUCTION: Bone marrow transplantation (BMT) is a complex process regulated by different cytokines and growth factors. The pleiotropic cytokine IL-6 (Interleukin-6) and related cytokines of the same family acting on the common signal transducer gp130 are known to play a key role in bone marrow (BM) engraftment. In contrast, the exact signalling events that control IL-6/gp130-driven haematopoietic stem cell development during BMT remain unresolved. METHODS: Conditional gp130 knockout and knockin mice were used to delete gp130 expression (gp130(ΔMx)), or to selectively disrupt gp130-dependent Ras (gp130(ΔMxRas)) or STAT signalling (gp130(ΔMxSTAT)) in BM cells. BM derived from the respective strains was transplanted into irradiated wildtype hosts and repopulation of various haematopoietic lineages was monitored by flow cytometry. RESULTS: BM derived from gp130 deficient donor mice (gp130(ΔMx)) displayed a delayed engraftment, as evidenced by reduced total white blood cells (WBC), marked thrombocytopenia and anaemia in the early phase after BMT. Lineage analysis unravelled a restricted development of CD4(+) and CD8(+) T-cells, CD19(+) B-cells and CD11b(+) myeloid cells after transplantation of gp130-deficient BM grafts. To further delineate the two major gp130-induced signalling cascades, Ras-MAPK and STAT1/3-signalling respectively, we used gp130(ΔMxRas) and gp130(ΔMxSTAT) donor BM. BMT of gp130(ΔMxSTAT) cells significantly impaired engraftment of CD4(+), CD8(+), CD19(+) and CD11b(+) cells, whereas gp130(ΔMxRas) BM displayed a selective impairment in early thrombopoiesis. Importantly, gp130-STAT1/3 signalling deficiency in BM grafts severely impaired survival of transplanted mice, thus demonstrating a pivotal role for this pathway in BM graft survival and function. CONCLUSION: Our data unravel a vital function of IL-6/gp130-STAT1/3 signals for BM engraftment and haematopoiesis, as well as for host survival after transplantation. STAT1/3 and ras-dependent pathways thereby exert distinct functions on individual bone-marrow-lineages

Promoting sexual and reproductive health among adolescents in southern and eastern Africa (PREPARE): project design and conceptual framework

Background: Young people in sub-Saharan Africa are affected by the HIV pandemic to a greater extent than young people elsewhere and effective HIV-preventive intervention programmes are urgently needed. The present article presents the rationale behind an EU-funded research project (PREPARE) examining effects of community-based (school delivered) interventions conducted in four sites in sub-Saharan Africa. One intervention focuses on changing beliefs and cognitions related to sexual practices (Mankweng, Limpopo, South Africa). Another promotes improved parent-offspring communication on sexuality (Kampala, Uganda). Two further interventions are more comprehensive aiming to promote healthy sexual practices. One of these (Western Cape, South Africa) also aims to reduce intimate partner violence while the other (Dar es Salaam, Tanzania) utilises school-based peer education. Methods/design: A modified Intervention Mapping approach is used to develop all programmes. Cluster randomised controlled trials of programmes delivered to school students aged 12–14 will be conducted in each study site. Schools will be randomly allocated (after matching or stratification) to intervention and delayed intervention arms. Baseline surveys at each site are followed by interventions and then by one (Kampala and Limpopo) or two (Western Cape and Dar es Salaam) post-intervention data collections. Questionnaires include questions common for all sites and are partly based on a set of social cognition models previously applied to the study of HIV-preventive behaviours. Data from all sites will be merged in order to compare prevalence and associations across sites on core variables. Power is set to .80 or higher and significance level to .05 or lower in order to detect intervention effects. Intraclass correlations will be estimated from previous surveys carried out at each site. Discussion: We expect PREPARE interventions to have an impact on hypothesized determinants of risky sexual behaviour and in Western Cape and Dar es Salaam to change sexual practices. Results from PREPARE will (i) identify modifiable cognitions and social processes related to risky sexual behaviour and (ii) identify promising intervention approaches among young adolescents in sub-Saharan cultures and contexts.publishedVersionPeer Reviewe

SARS-CoV-2 Proteome-Wide Analysis Revealed Significant Epitope Signatures in COVID-19 Patients

The WHO declared the COVID-19 outbreak a public health emergency of international concern. The causative agent of this acute respiratory disease is a newly emerged coronavirus, named SARS-CoV-2, which originated in China in late 2019. Exposure to SARS-CoV-2 leads to multifaceted disease outcomes from asymptomatic infection to severe pneumonia, acute respiratory distress and potentially death. Understanding the host immune response is crucial for the development of interventional strategies. Humoral responses play an important role in defending viral infections and are therefore of particular interest. With the aim to resolve SARS-CoV-2-specific humoral immune responses at the epitope level, we screened clinically well-characterized sera from COVID-19 patients with mild and severe disease outcome using high-density peptide microarrays covering the entire proteome of SARS-CoV-2. Moreover, we determined the longevity of epitope-specific antibody responses in a longitudinal approach. Here we present IgG and IgA-specific epitope signatures from COVID-19 patients, which may serve as discriminating prognostic or predictive markers for disease outcome and/or could be relevant for intervention strategies

The common HAQ STING variant impairs cGAS-dependent antibacterial responses and is associated with susceptibility to Legionnaires’ disease in humans

Abstract The cyclic GMP-AMP synthase (cGAS)-STING pathway is central for innate immune sensing of various bacterial, viral and protozoal infections. Recent studies identified the common HAQ and R232H alleles of TMEM173/STING, but the functional consequences of these variants for primary infections are unknown. Here we demonstrate that cGAS- and STING-deficient murine macrophages as well as human cells of individuals carrying HAQ TMEM173/STING were severely impaired in producing type I IFNs and pro-inflammatory cytokines in response to Legionella pneumophila, bacterial DNA or cyclic dinucleotides (CDNs). In contrast, R232H attenuated cytokine production only following stimulation with bacterial CDN, but not in response to L. pneumophila or DNA. In a mouse model of Legionnaires’ disease, cGAS- and STING-deficient animals exhibited higher bacterial loads as compared to wild-type mice. Moreover, the haplotype frequency of HAQ TMEM173/STING, but not of R232H TMEM173/STING, was increased in two independent cohorts of human Legionnaires’ disease patients as compared to healthy controls. Our study reveals that the cGAS-STING cascade contributes to antibacterial defense against L. pneumophila in mice and men, and provides important insight into how the common HAQ TMEM173/STING variant affects antimicrobial immune responses and susceptibility to infection. Trial registration ClinicalTrials.gov DRKS00005274, German Clinical Trials Register Author summary Interferons (IFNs) and pro-inflammatory cytokines are key regulators of gene expression and antibacterial defense during Legionella pneumophila infection. Here we demonstrate that production of these mediators was largely or partly dependent on the cyclic GMP-AMP synthase (cGAS)-STING pathway in human and murine cells. Cells of individuals carrying the common HAQ allele of TMEM173/STING were strongly impaired in their ability to respond to L. pneumophila, bacterial DNA or cyclic dinucleotides (CDNs), whereas the R232H allele was only attenuated in sensing of exogenous CDNs. Importantly, cGAS and STING contributed to antibacterial defense in mice during L. pneumophila lung infection, and the allele frequency of HAQ TMEM173/STING, but not of R232H TMEM173/STING, was increased in two independent cohorts of human Legionnaires’ disease patients as compared to healthy controls. Hence, sensing of bacterial DNA by the cGAS/STING pathway contributes to antibacterial defense against L. pneumophila infection, and the hypomorphic variant HAQ TMEM173/STING is associated with increased susceptibility to Legionnaires’ disease in humans

CD169/SIGLEC1 is expressed on circulating monocytes in COVID-19 and expression levels are associated with disease severity

Coronavirus disease 2019 (COVID-19) is caused by infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Type I interferons are important in the defense of viral infections. Recently, neutralizing IgG auto-antibodies against type I interferons were found in patients with severe COVID-19 infection. Here, we analyzed expression of CD169/SIGLEC1, a well described downstream molecule in interferon signaling, and found increased monocytic CD169/SIGLEC1 expression levels in patients with mild, acute COVID-19, compared to patients with severe disease. We recommend further clinical studies to evaluate the value of CD169/SIGLEC1 expression in patients with COVID-19 with or without auto-antibodies against type I interferons

Impact of dexamethasone on SARS-CoV-2 concentration kinetics and antibody response in hospitalized COVID-19 patients: results from a prospective observational study.

OBJECTIVES: Dexamethasone has become the standard of care for severe coronavirus disease 2019 (COVID-19), but its virological impact is poorly understood. The objectives of this work were to characterize the kinetics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) concentration in the upper respiratory tract (URT) and the antibody response in patients with (D+) and without (D-) dexamethasone treatment. METHODS: Data and biosamples from hospitalized patients with severe COVID-19, enrolled between 4th March and 11th December 2020 in a prospective observational study, were analysed. SARS-CoV-2 virus concentration in serial URT samples was measured using RT-PCR. SARS-CoV-2-specific immunoglobulins A and G (IgA and IgG) were measured in serum samples using S1-ELISA. RESULTS: We compared 101 immunocompetent patients who received dexamethasone (according to the inclusion criteria and dosage determined in the RECOVERY trial) to 93 immunocompetent patients with comparable disease severity from the first months of the pandemic, who had not been treated with dexamethasone or other glucocorticoids. We found no inter-group differences in virus concentration kinetics, duration of presence of viral loads >106 viral copies/mL (D+ median 17 days (IQR 13-24), D- 19 days (IQR 13-29)), or time from symptom onset until seroconversion (IgA: D+ median 11.5 days (IQR 11-12), D- 14 days (IQR 11.5-15.75); IgG: D+ 13 days (IQR 12-14.5), D- 12 days (IQR 11-15)). CONCLUSION: Dexamethasone does not appear to lead to a change in virus clearance or a delay in antibody response in immunocompetent patients hospitalized with severe COVID-19

IFNs Modify the Proteome of <i>Legionella</i>-Containing Vacuoles and Restrict Infection Via IRG1-Derived Itaconic Acid

Macrophages can be niches for bacterial pathogens or antibacterial effector cells depending on the pathogen and signals from the immune system. Here we show that type I and II IFNs are master regulators of gene expression during Legionella pneumophila infection, and activators of an alveolar macrophage-intrinsic immune response that restricts bacterial growth during pneumonia. Quantitative mass spectrometry revealed that both IFNs substantially modify Legionella-containing vacuoles, and comparative analyses reveal distinct subsets of transcriptionally and spatially IFN-regulated proteins. Immune-responsive gene (IRG)1 is induced by IFNs in mitochondria that closely associate with Legionella-containing vacuoles, and mediates production of itaconic acid. This metabolite is bactericidal against intravacuolar L. pneumophila as well as extracellular multidrug-resistant Gram-positive and -negative bacteria. Our study explores the overall role IFNs play in inducing substantial remodeling of bacterial vacuoles and in stimulating production of IRG1-derived itaconic acid which targets intravacuolar pathogens. IRG1 or its product itaconic acid might be therapeutically targetable to fight intracellular and drug-resistant bacteria

Heart failure with preserved ejection fraction according to the HFA-PEFF score in COVID-19 patients: clinical correlates and echocardiographic findings

Aims: Viral-induced cardiac inflammation can induce heart failure with preserved ejection fraction (HFpEF)-like syndromes. COVID-19 can lead to myocardial damage and vascular injury. We hypothesised that COVID-19 patients frequently develop a HFpEF-like syndrome, and designed this study to explore this. Methods and results: Cardiac function was assessed in 64 consecutive, hospitalized, and clinically stable COVID-19 patients from April-November 2020 with left ventricular ejection fraction (LVEF) ≥50% (age 56 ± 19 years, females: 31%, severe COVID-19 disease: 69%). To investigate likelihood of HFpEF presence, we used the HFA-PEFF score. A low (0-1 points), intermediate (2-4 points), and high (5-6 points) HFA-PEFF score was observed in 42%, 33%, and 25% of patients, respectively. In comparison, 64 subjects of similar age, sex, and comorbidity status without COVID-19 showed these scores in 30%, 66%, and 4%, respectively (between groups: P = 0.0002). High HFA-PEFF scores were more frequent in COVID-19 patients than controls (25% vs. 4%, P = 0.001). In COVID-19 patients, the HFA-PEFF score significantly correlated with age, estimated glomerular filtration rate, high-sensitivity troponin T (hsTnT), haemoglobin, QTc interval, LVEF, mitral E/A ratio, and H2 FPEF score (all P < 0.05). In multivariate, ordinal regression analyses, higher age and hsTnT were significant predictors of increased HFA-PEFF scores. Patients with myocardial injury (hsTnT ≥14 ng/L: 31%) vs. patients without myocardial injury, showed higher HFA-PEFF scores [median 5 (interquartile range 3-6) vs. 1 (0-3), P < 0.001] and more often showed left ventricular diastolic dysfunction (75% vs. 27%, P < 0.001). Conclusion: Hospitalized COVID-19 patients frequently show high likelihood of presence of HFpEF that is associated with cardiac structural and functional alterations, and myocardial injury. Detailed cardiac assessments including echocardiographic determination of left ventricular diastolic function and biomarkers should become routine in the care of hospitalized COVID-19 patients