Now showing items 1-20 of 3891

    • Reducing burden from respiratory infections in refugees and immigrants: a systematic review of interventions in OECD, EU, EEA and EU-applicant countries.

      Lambert, Jan-Frederic; Stete, Katarina; Balmford, James; Bockey, Annabelle; Kern, Winfried; Rieg, Siegbert; Boeker, Martin; Lange, Berit; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (BMC, 2021-08-26)
      Background: Respiratory diseases are a major reason for refugees and other immigrants seeking health care in countries of arrival. The burden of respiratory diseases in refugees is exacerbated by sometimes poor living conditions characterised by crowding in mass accommodations and basic living portals. The lack of synthesised evidence and guideline-relevant information to reduce morbidity and mortality from respiratory infections endangers this population. Methods: A systematic review of all controlled and observational studies assessing interventions targeting the treatment, diagnosis and management of respiratory infections in refugees and immigrants in OECD, EU, EEA and EU-applicant countries published between 2000 and 2019 in MEDLINE, CINAHL, PSYNDEX and the Web of Science. Results: Nine of 5779 identified unique records met our eligibility criteria. Seven studies reported an increase in vaccine coverage from 2 to 52% after educational multilingual interventions for respiratory-related childhood diseases (4 studies) and for influenza (5 studies). There was limited evidence in one study that hand sanitiser reduced rates of upper respiratory infections and when provided together with face masks also the rates of influenza-like-illness in a hard to reach migrant neighbourhood. In outbreak situations of vaccine-preventable diseases, secondary cases and outbreak hazards were reduced by general vaccination strategies early after arrival but not by serological testing after exposure (1 study). We identified evidence gaps regarding interventions assessing housing standards, reducing burden of bacterial pneumonia and implementation of operational standards in refugee care and reception centres. Conclusions: Multilingual health literacy interventions should be considered to increase uptake of vaccinations in refugees and immigrants. Immediate vaccinations upon arrival at refugee housings may reduce secondary infections and outbreaks. Well-designed controlled studies on housing and operational standards in refugee and immigrant populations early after arrival as well as adequate ways to gain informed consent for early vaccinations in mass housings is required to inform guidelines.
    • Transient Depletion of Foxp3 Regulatory T Cells Selectively Promotes Aggressive β Cell Autoimmunity in Genetically Susceptible DEREG Mice.

      Watts, Deepika; Janßen, Marthe; Jaykar, Mangesh; Palmucci, Francesco; Weigelt, Marc; Petzold, Cathleen; Hommel, Angela; Sparwasser, Tim; Bonifacio, Ezio; Kretschmer, Karsten; et al. (Frontiers, 2021-08-10)
      Type 1 diabetes (T1D) represents a hallmark of the fatal multiorgan autoimmune syndrome affecting humans with abrogated Foxp3+ regulatory T (Treg) cell function due to Foxp3 gene mutations, but whether the loss of Foxp3+ Treg cell activity is indeed sufficient to promote β cell autoimmunity requires further scrutiny. As opposed to human Treg cell deficiency, β cell autoimmunity has not been observed in non-autoimmune-prone mice with constitutive Foxp3 deficiency or after diphtheria toxin receptor (DTR)-mediated ablation of Foxp3+ Treg cells. In the spontaneous nonobese diabetic (NOD) mouse model of T1D, constitutive Foxp3 deficiency did not result in invasive insulitis and hyperglycemia, and previous studies on Foxp3+ Treg cell ablation focused on Foxp3DTR NOD mice, in which expression of a transgenic BDC2.5 T cell receptor (TCR) restricted the CD4+ TCR repertoire to a single diabetogenic specificity. Here we revisited the effect of acute Foxp3+ Treg cell ablation on β cell autoimmunity in NOD mice in the context of a polyclonal TCR repertoire. For this, we took advantage of the well-established DTR/GFP transgene of DEREG mice, which allows for specific ablation of Foxp3+ Treg cells without promoting catastrophic autoimmune diseases. We show that the transient loss of Foxp3+ Treg cells in prediabetic NOD.DEREG mice is sufficient to precipitate severe insulitis and persistent hyperglycemia within 5 days after DT administration. Importantly, DT-treated NOD.DEREG mice preserved many clinical features of spontaneous diabetes progression in the NOD model, including a prominent role of diabetogenic CD8+ T cells in terminal β cell destruction. Despite the severity of destructive β cell autoimmunity, anti-CD3 mAb therapy of DT-treated mice interfered with the progression to overt diabetes, indicating that the novel NOD.DEREG model can be exploited for preclinical studies on T1D under experimental conditions of synchronized, advanced β cell autoimmunity. Overall, our studies highlight the continuous requirement of Foxp3+ Treg cell activity for the control of genetically pre-installed autoimmune diabetes.
    • Cortactin Is Required for Efficient FAK, Src and Abl Tyrosine Kinase Activation and Phosphorylation of CagA.

      Knorr, Jakob; Sharafutdinov, Irshad; Fiedler, Florian; Soltan Esmaeili, Delara; Rohde, Manfred; Rottner, Klemens; Backert, Steffen; Tegtmeyer, Nicole; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (MDPI, 2021-06-03)
      Cortactin is a well-known regulatory protein of the host actin cytoskeleton and represents an attractive target of microbial pathogens like Helicobacter pylori. H. pylori manipulates cortactin's phosphorylation status by type-IV secretion-dependent injection of its virulence protein CagA. Multiple host tyrosine kinases, like FAK, Src, and Abl, are activated during infection, but the pathway(s) involved is (are) not yet fully established. Among them, Src and Abl target CagA and stimulate tyrosine phosphorylation of the latter at its EPIYA-motifs. To investigate the role of cortactin in more detail, we generated a CRISPR/Cas9 knockout of cortactin in AGS gastric epithelial cells. Surprisingly, we found that FAK, Src, and Abl kinase activities were dramatically downregulated associated with widely diminished CagA phosphorylation in cortactin knockout cells compared to the parental control. Together, we report here a yet unrecognized cortactin-dependent signaling pathway involving FAK, Src, and Abl activation, and controlling efficient phosphorylation of injected CagA during infection. Thus, the cortactin status could serve as a potential new biomarker of gastric cancer development.
    • A molecular theory of germinal center B cell selection and division.

      Meyer-Hermann, Michael; BRICS, Braunschweiger Zentrum für Systembiologie, Rebenring 56,38106 Braunschweig, Germany. (Cell Press, 2021-08-24)
      The selection of B cells (BCs) in germinal centers (GCs) is pivotal to the generation of high-affinity antibodies and memory BCs, but it lacks global understanding. Based on the idea of a single Tfh-cell signal that controls BC selection and division, experiments appear contradictory. Here, we use the current knowledge on the molecular pathways of GC BCs to develop a theory of GC BC selection and division based on the dynamics of molecular factors. This theory explains the seemingly contradictory experiments by the separation of signals for BC fate decision from signals controlling the number of BC divisions. Three model variants are proposed and experiments are predicted that allow one to distinguish those. Understanding information processing in molecular BC states is critical for targeted immune interventions, and the proposed theory implies that selection and division can be controlled independently in GC reactions.
    • Streptomonospora litoralis sp. nov., a halophilic thiopeptides producer isolated from sand collected at Cuxhaven beach.

      Khodamoradi, Shadi; Hahnke, Richard L; Mast, Yvonne; Schumann, Peter; Kämpfer, Peter; Steinert, Michael; Rückert, Christian; Surup, Frank; Rohde, Manfred; Wink, Joachim; et al. (Springer, 2021-08-06)
      Strain M2T was isolated from the beach of Cuxhaven, Wadden Sea, Germany, in course of a program to attain new producers of bioactive natural products. Strain M2T produces litoralimycin and sulfomycin-type thiopeptides. Bioinformatic analysis revealed a potential biosynthetic gene cluster encoding for the M2T thiopeptides. The strain is Gram-stain-positive, rod shaped, non-motile, spore forming, showing a yellow colony color and forms extensively branched substrate mycelium and aerial hyphae. Inferred from the 16S rRNA gene phylogeny strain M2T affiliates with the genus Streptomonospora. It shows 96.6% 16S rRNA gene sequence similarity to the type species Streptomonospora salina DSM 44593 T and forms a distinct branch with Streptomonospora sediminis DSM 45723 T with 97.0% 16S rRNA gene sequence similarity. Genome-based phylogenetic analysis revealed that M2T is closely related to Streptomonospora alba YIM 90003 T with a digital DNA-DNA hybridisation (dDDH) value of 26.6%. The predominant menaquinones of M2T are MK-10(H6), MK-10(H8), and MK-11(H6) (> 10%). Major cellular fatty acids are iso-C16:0, anteiso C17:0 and C18:0 10-methyl. The polar lipid profile consisted of diphosphatidylglycerol phosphatidyl glycerol, phosphatidylinositol, phosphatidylcholine, phosphatidylethanolamine, three glycolipids, two unknown phospholipids, and two unknown lipids. The genome size of type strain M2T is 5,878,427 bp with 72.1 mol % G + C content. Based on the results obtained from phylogenetic and chemotaxonomic studies, strain M2T (= DSM 106425 T = NCCB 100650 T) is considered to represent a novel species within the genus Streptomonospora for which the name Streptomonospora litoralis sp. nov. is proposed.
    • Recent Developments on the Synthesis and Bioactivity of Ilamycins/Rufomycins and Cyclomarins, Marine Cyclopeptides That Demonstrate Anti-Malaria and Anti-Tuberculosis Activity.

      Kazmaier, Uli; Junk, Lukas; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (MDPI, 2021-08-03)
      Ilamycins/rufomycins and cyclomarins are marine cycloheptapeptides containing unusual amino acids. Produced by Streptomyces sp., these compounds show potent activity against a range of mycobacteria, including multidrug-resistant strains of Mycobacterium tuberculosis. The cyclomarins are also very potent inhibitors of Plasmodium falciparum. Biosynthetically the cyclopeptides are obtained via a heptamodular nonribosomal peptide synthetase (NRPS) that directly incorporates some of the nonproteinogenic amino acids. A wide range of derivatives can be obtained by fermentation, while bioengineering also allows the mutasynthesis of derivatives, especially cyclomarins. Other derivatives are accessible by semisynthesis or total syntheses, reported for both natural product classes. The anti-tuberculosis (anti-TB) activity results from the binding of the peptides to the N-terminal domain (NTD) of the bacterial protease-associated unfoldase ClpC1, causing cell death by the uncontrolled proteolytic activity of this enzyme. Diadenosine triphosphate hydrolase (PfAp3Aase) was found to be the active target of the cyclomarins in Plasmodia. SAR studies with natural and synthetic derivatives on ilamycins/rufomycins and cyclomarins indicate which parts of the molecules can be simplified or otherwise modified without losing activity for either target. This review examines all aspects of the research conducted in the syntheses of these interesting cyclopeptides.
    • HBV-RNA Co-amplification May Influence HBV DNA Viral Load Determination.

      Maasoumy, Benjamin; Geretti, Anna Maria; Frontzek, André; Austin, Harrison; Aretzweiler, Gudrun; Garcia-Álvarez, Monica; Leuchter, Susanne; Simon, Christian O; Marins, Ed G; Canchola, Jesse A; et al. (Wiley, 2020-05-26)
      Despite effective hepatitis B virus (HBV)-DNA suppression, HBV RNA can circulate in patients receiving nucleoside/nucleotide analogues (NAs). Current assays quantify HBV DNA by either real-time polymerase chain reaction (PCR), which uses DNA polymerase, or transcription-mediated amplification, which uses reverse-transcriptase (RT) and RNA polymerase. We assessed the effect of RT capability on HBV-DNA quantification in samples from three cohorts, including patients with quantified HBV RNA. We compared the HBV-DNA levels by real-time PCR (cobas HBV, Roche 6800/8800; Xpert HBV, Cepheid), transcription-mediated amplification (Aptima HBV, Hologic), and real-time PCR with added RT capability (cobas HBV+RT). In the first cohort (n = 45) followed over 192 weeks of NA therapy, on-treatment HBV-DNA levels were higher with cobas HBV+RT than cobas HBV (mean difference: 0.14 log10 IU/mL). In a second cohort (n = 50) followed over 96 weeks of NA therapy, HBV-DNA viral load was significantly higher with the cobas HBV+RT and Aptima HBV compared with the cobas HBV test at all time points after initiation of NA therapy (mean difference: 0.65-1.16 log10 IU/mL). A clinically significant difference was not detected between the assays at baseline. In a third cohort (n = 53), after a median of 2.2 years of NA therapy, we detected HBV RNA (median 5.6 log10 copies/mL) in 23 patients (43.4%). Median HBV-DNA levels by Aptima HBV were 2.4 versus less than 1 log10 IU/mL in samples with HBV RNA and without HBV RNA, respectively (P = 0.0006). In treated patients with HBV RNA, Aptima HBV measured higher HBV-DNA levels than Xpert HBV and cobas HBV. Conclusion: Tests including an RT step may overestimate HBV DNA, particularly in samples with low viral loads as a result of NA therapy. This overestimation is likely due to amplification of HBV RNA and may have an impact on clinical decisions.
    • MicroRNA-125b-5p Regulates Hepatocyte Proliferation During the Termination Phase of Liver Regeneration.

      Yang, Dakai; Dai, Zhen; Yang, Taihua; Balakrishnan, Asha; Yuan, Qinggong; Vondran, Florian W R; Manns, Michael P; Ott, Michael; Cantz, Tobias; Sharma, Amar Deep; et al. (Wiley, 2020-09-15)
      The ability of the liver to regenerate and restore mass limits the increasing mortality rate due to life-threatening liver diseases. Successful liver regeneration is accomplished in multiple stages, of which the priming and proliferation phases are well studied. However, the regulatory pathways, specifically microRNA (miRNA)-mediated posttranscriptional regulation, which prevent uncontrolled proliferation and mediate the termination of liver regeneration, are not well understood. We identified differentially regulated miRNAs during the termination phase after 2/3 partial hepatectomy (PH) in mice, which is a well-established mouse model of liver regeneration. We further evaluated the function of differentially regulated miRNAs in primary mouse hepatocytes by using mimics and inhibitors and in vivo by using adeno-associated virus (AAV) serotype 8. A candidate miRNA target was identified by messenger RNA array in silico analyses and validated in primary mouse and human hepatocytes. Using miRNA profiling, we discovered miR-125b-5p as a novel regulator of hepatocyte proliferation in the late phase of liver regeneration. AAV-mediated miR-125b-5p delivery in mice enhanced the endogenous regenerative capacity and resulted in improved restoration of liver mass after 2/3 PH. Further, we found that ankyrin repeat and BTB/POZ domain containing protein 1 (Abtb1) is a direct target of miR-125b-5p in primary mouse and human hepatocytes and contributes to the pro-proliferative activity of miR-125b-5p by forkhead box G1 (FOXG1) and the cyclin-dependent kinase inhibitor 1A (p21) pathway. Conclusion: miR-125b-5p has an important role in regulating hepatocyte proliferation in the termination phase of liver regeneration and may serve as a potential therapeutic target in various liver diseases that often exhibit deregulated hepatocyte proliferation.
    • Fusarium: more than a node or a foot-shaped basal cell.

      Crous, P W; Lombard, L; Sandoval-Denis, M; Seifert, K A; Schroers, H-J; Chaverri, P; Gené, J; Guarro, J; Hirooka, Y; Bensch, K; et al. (Elsevier BV, 2021-08-17)
      Recent publications have argued that there are potentially serious consequences for researchers in recognising distinct genera in the terminal fusarioid clade of the family Nectriaceae. Thus, an alternate hypothesis, namely a very broad concept of the genus Fusarium was proposed. In doing so, however, a significant body of data that supports distinct genera in Nectriaceae based on morphology, biology, and phylogeny is disregarded. A DNA phylogeny based on 19 orthologous protein-coding genes was presented to support a very broad concept of Fusarium at the F1 node in Nectriaceae. Here, we demonstrate that re-analyses of this dataset show that all 19 genes support the F3 node that represents Fusarium sensu stricto as defined by F. sambucinum (sexual morph synonym Gibberella pulicaris). The backbone of the phylogeny is resolved by the concatenated alignment, but only six of the 19 genes fully support the F1 node, representing the broad circumscription of Fusarium. Furthermore, a re-analysis of the concatenated dataset revealed alternate topologies in different phylogenetic algorithms, highlighting the deep divergence and unresolved placement of various Nectriaceae lineages proposed as members of Fusarium. Species of Fusarium s. str. are characterised by Gibberella sexual morphs, asexual morphs with thin- or thick-walled macroconidia that have variously shaped apical and basal cells, and trichothecene mycotoxin production, which separates them from other fusarioid genera. Here we show that the Wollenweber concept of Fusarium presently accounts for 20 segregate genera with clear-cut synapomorphic traits, and that fusarioid macroconidia represent a character that has been gained or lost multiple times throughout Nectriaceae. Thus, the very broad circumscription of Fusarium is blurry and without apparent synapomorphies, and does not include all genera with fusarium-like macroconidia, which are spread throughout Nectriaceae (e.g., Cosmosporella, Macroconia, Microcera). In this study four new genera are introduced, along with 18 new species and 16 new combinations. These names convey information about relationships, morphology, and ecological preference that would otherwise be lost in a broader definition of Fusarium. To assist users to correctly identify fusarioid genera and species, we introduce a new online identification database, Fusarioid-ID, accessible at www.fusarium.org. The database comprises partial sequences from multiple genes commonly used to identify fusarioid taxa (act1, CaM, his3, rpb1, rpb2, tef1, tub2, ITS, and LSU). In this paper, we also present a nomenclator of names that have been introduced in Fusarium up to January 2021 as well as their current status, types, and diagnostic DNA barcode data. In this study, researchers from 46 countries, representing taxonomists, plant pathologists, medical mycologists, quarantine officials, regulatory agencies, and students, strongly support the application and use of a more precisely delimited Fusarium (= Gibberella) concept to accommodate taxa from the robust monophyletic node F3 on the basis of a well-defined and unique combination of morphological and biochemical features. This F3 node includes, among others, species of the F. fujikuroi, F. incarnatum-equiseti, F. oxysporum, and F. sambucinum species complexes, but not species of Bisifusarium [F. dimerum species complex (SC)], Cyanonectria (F. buxicola SC), Geejayessia (F. staphyleae SC), Neocosmospora (F. solani SC) or Rectifusarium (F. ventricosum SC). The present study represents the first step to generating a new online monograph of Fusarium and allied fusarioid genera (www.fusarium.org).
    • Defective interferon amplification and impaired host responses against influenza virus in obese mice.

      Gaur, Pratibha; Riehn, Mathias; Zha, Lisha; Köster, Mario; Hauser, Hansjörg; Wirth, Dagmar; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Wiley, 2021-07-07)
      Objective: Obesity is a major risk factor that increases morbidity and mortality upon infection. Although type I and type III interferon (IFN)-induced innate immune responses represent the first line of defense against viral infections, their functionality in the context of metabolic disorders remains largely obscure. This study aimed to investigate IFN responses upon respiratory viral infection in obese mice. Methods: The activation of IFNs as well as IFN regulatory factors (IRFs) upon H3N2 influenza infection in mice upon high-fat-diet feeding was investigated. Results: Influenza infection of obese mice was characterized by higher mortalities. In-depth analysis revealed impaired induction of both type I and type III IFNs as well as markedly reduced IFN responses. Notably, it was found that IRF7 gene expression in obese animals was reduced in homeostasis, and its induction by the virus was strongly attenuated. Conclusions: The results suggest that the attenuated IRF7 expression and induction are responsible for the reduced expression levels of type I and III IFNs and, thus, for the higher susceptibility and severity of respiratory infections in obese mice.
    • In Vivo Lentiviral Gene Delivery of HLA-DR and Vaccination of Humanized Mice for Improving the Human T and B Cell Immune Reconstitution.

      Kumar, Suresh; Koenig, Johannes; Schneider, Andreas; Wermeling, Fredrik; Boddul, Sanjaykumar; Theobald, Sebastian J; Vollmer, Miriam; Kloos, Doreen; Lachmann, Nico; Klawonn, Frank; et al. (MDPI, 2021-08-05)
      Humanized mouse models generated with human hematopoietic stem cells (HSCs) and reconstituting the human immune system (HIS-mice) are invigorating preclinical testing of vaccines and immunotherapies. We have recently shown that human engineered dendritic cells boosted bonafide human T and B cell maturation and antigen-specific responses in HIS-mice. Here, we evaluated a cell-free system based on in vivo co-delivery of lentiviral vectors (LVs) for expression of a human leukocyte antigen (HLA-DRA*01/ HLA-DRB1*0401 functional complex, "DR4"), and a LV vaccine expressing human cytokines (GM-CSF and IFN-α) and a human cytomegalovirus gB antigen (HCMV-gB). Humanized NOD/Rag1null/IL2Rγnull (NRG) mice injected by i.v. with LV-DR4/fLuc showed long-lasting (up to 20 weeks) vector distribution and expression in the spleen and liver. In vivo administration of the LV vaccine after LV-DR4/fLuc delivery boosted the cellularity of lymph nodes, promoted maturation of terminal effector CD4+ T cells, and promoted significantly higher development of IgG+ and IgA+ B cells. This modular lentigenic system opens several perspectives for basic human immunology research and preclinical utilization of LVs to deliver HLAs into HIS-mice.
    • Within-Host Adaptation of in a Bovine Mastitis Infection Is Associated with Increased Cytotoxicity.

      Mayer, Katharina; Kucklick, Martin; Marbach, Helene; Ehling-Schulz, Monika; Engelmann, Susanne; Grunert, Tom; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (MDPI, 2021-08-17)
      Within-host adaptation is a typical feature of chronic, persistent Staphylococcus aureus infections. Research projects addressing adaptive changes due to bacterial in-host evolution increase our understanding of the pathogen's strategies to survive and persist for a long time in various hosts such as human and bovine. In this study, we investigated the adaptive processes of S. aureus during chronic, persistent bovine mastitis using a previously isolated isogenic strain pair from a dairy cow with chronic, subclinical mastitis, in which the last variant (host-adapted, Sigma factor SigB-deficient) quickly replaced the initial, dominant variant. The strain pair was cultivated under specific in vitro infection-relevant growth-limiting conditions (iron-depleted RPMI under oxygen limitation). We used a combinatory approach of surfaceomics, molecular spectroscopic fingerprinting and in vitro phenotypic assays. Cellular cytotoxicity assays using red blood cells and bovine mammary epithelial cells (MAC-T) revealed changes towards a more cytotoxic phenotype in the host-adapted isolate with an increased alpha-hemolysin (α-toxin) secretion, suggesting an improved capacity to penetrate and disseminate the udder tissue. Our results foster the hypothesis that within-host evolved SigB-deficiency favours extracellular persistence in S. aureus infections. Here, we provide new insights into one possible adaptive strategy employed by S. aureus during chronic, bovine mastitis, and we emphasise the need to analyse genotype-phenotype associations under different infection-relevant growth conditions.
    • Mesenteric Lymph Node Transplantation in Mice to Study Immune Responses of the Gastrointestinal Tract.

      Shaikh, Haroon; Vargas, Juan Gamboa; Mokhtari, Zeinab; Jarick, Katja J; Ulbrich, Maria; Mosca, Josefina Peña; Viera, Estibaliz Arellano; Graf, Caroline; Le, Duc-Dung; Heinze, Katrin G; et al. (Frontiers, 2021-07-26)
      Mesenteric lymph nodes (mLNs) are sentinel sites of enteral immunosurveillance and immune homeostasis. Immune cells from the gastrointestinal tract (GIT) are constantly recruited to the mLNs in steady-state and under inflammatory conditions resulting in the induction of tolerance and immune cells activation, respectively. Surgical dissection and transplantation of lymph nodes (LN) is a technique that has supported seminal work to study LN function and is useful to investigate resident stromal and endothelial cell biology and their cellular interactions in experimental disease models. Here, we provide a detailed protocol of syngeneic mLN transplantation and report assays to analyze effective mLN engraftment in congenic recipients. Transplanted mLNs allow to study T cell activation and proliferation in preclinical mouse models. Donor mLNs proved viable and functional after surgical transplantation and regenerated blood and lymphatic vessels. Immune cells from the host completely colonized the transplanted mLNs within 7-8 weeks after the surgical intervention. After allogeneic hematopoietic cell transplantation (allo-HCT), adoptively transferred allogeneic CD4+ T cells from FVB/N (H-2q) mice homed to the transplanted mLNs in C57BL/6 (H-2b) recipients during the initiation phase of acute graft-versus-host disease (aGvHD). These CD4+ T cells retained full proliferative capacity and upregulated effector and gut homing molecules comparable to those in mLNs from unmanipulated wild-type recipients. Wild type mLNs transplanted into MHCII deficient syngeneic hosts sufficed to activate alloreactive T cells upon allogeneic hematopoietic cell transplantation, even in the absence of MHCII+ CD11c+ myeloid cells. These data support that orthotopically transplanted mLNs maintain physiological functions after transplantation. The technique of LN transplantation can be applied to study migratory and resident cell compartment interactions in mLNs as well as immune reactions from and to the gut under inflammatory and non-inflammatory conditions.
    • Cellular and humoral immunogenicity of a SARS-CoV-2 mRNA vaccine in patients on haemodialysis.

      Strengert, Monika; Becker, Matthias; Ramos, Gema Morillas; Dulovic, Alex; Gruber, Jens; Juengling, Jennifer; Lürken, Karsten; Beigel, Andrea; Wrenger, Eike; Lonnemann, Gerhard; et al. (Elsevier, 2021-08-12)
      Background: Patients with chronic renal insufficiency on maintenance haemodialysis face an increased risk of COVID-19 induced mortality and impaired vaccine responses. To date, only a few studies have addressed SARS-CoV-2 vaccine elicited immunity in this immunocompromised population. Methods: We assessed immunogenicity of the mRNA vaccine BNT162b2 in at-risk dialysis patients and characterised systemic cellular and humoral immune responses in serum and saliva using interferon γ release assay and multiplex-based cytokine and immunoglobulin measurements. We further compared binding capacity and neutralization efficacy of vaccination-induced immunoglobulins against emerging SARS-CoV-2 variants Alpha, Beta, Epsilon and Cluster 5 by ACE2-RBD competition assay. Findings: Patients on maintenance haemodialysis exhibit detectable but variable cellular and humoral immune responses against SARS-CoV-2 and variants of concern after a two-dose regimen of BNT162b2. Although vaccination-induced immunoglobulins were detectable in saliva and plasma, both anti-SARS-CoV-2 IgG and neutralization efficacy was reduced compared to a vaccinated non-dialysed control population. Similarly, T-cell mediated interferon γ release after stimulation with SARS-CoV-2 spike peptides was significantly diminished. Interpretation: Quantifiable humoral and cellular immune responses after BNT162b2 vaccination in individuals on maintenance haemodialysis are encouraging, but urge for longitudinal follow-up to assess longevity of immunity. Diminished virus neutralization and interferon γ responses in the face of emerging variants of concern may favour this at-risk population for re-vaccination using modified vaccines at the earliest opportunity. Funding: Initiative and Networking Fund of the Helmholtz Association of German Research Centres, EU Horizon 2020 research and innovation program, State Ministry of Baden-Württemberg for Economic Affairs, Labour and Tourism.
    • A SARS-CoV-2 neutralizing antibody selected from COVID-19 patients binds to the ACE2-RBD interface and is tolerant to most known RBD mutations.

      Bertoglio, Federico; Fühner, Viola; Ruschig, Maximilian; Heine, Philip Alexander; Abassi, Leila; Klünemann, Thomas; Rand, Ulfert; Meier, Doris; Langreder, Nora; Steinke, Stephan; et al. (Cell Press, 2021-07-07)
      The novel betacoronavirus severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) causes a form of severe pneumonia disease called coronavirus disease 2019 (COVID-19). To develop human neutralizing anti-SARS-CoV-2 antibodies, antibody gene libraries from convalescent COVID-19 patients were constructed and recombinant antibody fragments (scFv) against the receptor-binding domain (RBD) of the spike protein were selected by phage display. The antibody STE90-C11 shows a subnanometer IC50 in a plaque-based live SARS-CoV-2 neutralization assay. The in vivo efficacy of the antibody is demonstrated in the Syrian hamster and in the human angiotensin-converting enzyme 2 (hACE2) mice model. The crystal structure of STE90-C11 Fab in complex with SARS-CoV-2-RBD is solved at 2.0 Å resolution showing that the antibody binds at the same region as ACE2 to RBD. The binding and inhibition of STE90-C11 is not blocked by many known emerging RBD mutations. STE90-C11-derived human IgG1 with FcγR-silenced Fc (COR-101) is undergoing Phase Ib/II clinical trials for the treatment of moderate to severe COVID-19.
    • The Small Protein YmoA Controls the Csr System and Adjusts Expression of Virulence-Relevant Traits of .

      Böhme, Katja; Heroven, Ann Kathrin; Lobedann, Stephanie; Guo, Yuzhu; Stolle, Anne-Sophie; Dersch, Petra; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Frontiers, 2021-08-03)
      Virulence gene expression of Yersinia pseudotuberculosis changes during the different stages of infection and this is tightly controlled by environmental cues. In this study, we show that the small protein YmoA, a member of the Hha family, is part of this process. It controls temperature- and nutrient-dependent early and later stage virulence genes in an opposing manner and co-regulates bacterial stress responses and metabolic functions. Our analysis further revealed that YmoA exerts this function by modulating the global post-transcriptional regulatory Csr system. YmoA pre-dominantly enhances the stability of the regulatory RNA CsrC. This involves a stabilizing stem-loop structure within the 5'-region of CsrC. YmoA-mediated CsrC stabilization depends on H-NS, but not on the RNA chaperone Hfq. YmoA-promoted reprogramming of the Csr system has severe consequences for the cell: we found that a mutant deficient of ymoA is strongly reduced in its ability to enter host cells and to disseminate to the Peyer's patches, mesenteric lymph nodes, liver and spleen in mice. We propose a model in which YmoA controls transition from the initial colonization phase in the intestine toward the host defense phase important for the long-term establishment of the infection in underlying tissues.
    • Phosphotyrosine couples peptide binding and SHP2 activation via a dynamic allosteric network.

      Marasco, Michelangelo; Kirkpatrick, John; Nanna, Vittoria; Sikorska, Justyna; Carlomagno, Teresa; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Elsevier, 2021-04-20)
      SHP2 is a ubiquitous protein tyrosine phosphatase, whose activity is regulated by phosphotyrosine (pY)-containing peptides generated in response to extracellular stimuli. Its crystal structure reveals a closed, auto-inhibited conformation in which the N-terminal Src homology 2 (N-SH2) domain occludes the catalytic site of the phosphatase (PTP) domain. High-affinity mono-phosphorylated peptides promote catalytic activity by binding to N-SH2 and disrupting the interaction with the PTP. The mechanism behind this process is not entirely clear, especially because N-SH2 is incapable of accommodating complete peptide binding when SHP2 is in the auto-inhibited state. Here, we show that pY performs an essential role in this process; in addition to its contribution to overall peptide-binding energy, pY-recognition leads to enhanced dynamics of the N-SH2 EF and BG loops via an allosteric communication network, which destabilizes the N-SH2–PTP interaction surface and simultaneously generates a fully accessible binding pocket for the C-terminal half of the phosphopeptide. Subsequently, full binding of the phosphopeptide is associated with the stabilization of activated SHP2. We demonstrate that this allosteric network exists only in N-SH2, which is directly involved in the regulation of SHP2 activity, while the C-terminal SH2 domain (C-SH2) functions primarily to recruit high-affinity bidentate phosphopeptides.
    • Antimicrobial resistance in patients with decompensated liver cirrhosis and bacterial infections in a tertiary center in Northern Germany.

      Hillert, Annika; Schultalbers, Marie; Tergast, Tammo L; Vonberg, Ralf-Peter; Rademacher, Jessica; Wedemeyer, Heiner; Cornberg, Markus; Ziesing, Stefan; Maasoumy, Benjamin; Höner Zu Siederdissen, Christoph; et al. (BMC, 2021-07-20)
      Background and aims: Bacterial infections are common in patients with decompensated liver cirrhosis and a leading cause of death. Reliable data on antibiotic resistance are required to initiate effective empiric therapy. We here aim to assess the antimicrobial resistance profile of bacteria among patients with liver cirrhosis and infection. Methods: Overall, 666 cirrhotic patients admitted to Hannover Medical School between January 2012 and April 2018 with ascites were assessed for bacterial infection. In case of infection, bacteria cultured from microbiological specimens of ascites, blood or urine were identified and analyzed for resistances against common antibiotic agents. Furthermore, analyses compared two periods of time and community-acquired vs. nosocomial infections. Results: In 281 patients with infection, microbiological sampling was performed and culture-positive results were obtained in 56.9%. Multidrug-resistant (MDR)-bacteria were found in 54 patients (19.2%). Gram-positive organisms were more common (n = 141/261, 54.0%) and detected in 116/192 culture-positive infections (60.4%). Comparing infections before and after 2015, a numerical decline for MDR-bacteria (23.8% vs. 15.6%, p = 0.08) was observed with a significant decline in meropenem resistance (34.9% vs. 19.5%, p = 0.03). MDR-bacteria were more frequent in the case of nosocomial infections. Of note, in ascites the majority of the tested bacteria were resistant against ceftriaxone (73.8%) whereas significantly less were resistant against meropenem (27.0%) and vancomycin (25.9%). Conclusions: In our tertiary center, distinct ratios of gram-positive infection with overall low ratios of MDR-bacteria were found. Adequate gram-positive coverage in the empiric therapy should be considered. Carbapenem treatment may be omitted even in nosocomial infection. In contrast, 3rd generation cephalosporins cannot be recommended even in community-acquired infection in our cirrhotic population.
    • The role of sirtuin 1 on the induction of trained immunity.

      Mourits, Vera P; Helder, Leonie S; Matzaraki, Vasiliki; Koeken, Valerie A C M; Groh, Laszlo; de Bree, L Charlotte J; Moorlag, Simone J C F M; van der Heijden, Charlotte D C C; Keating, Samuel T; van Puffelen, Jelmer H; et al. (Elsevier, 2021-06-12)
      Sirtuin 1 (SIRT1) has been described to modify immune responses by modulation of gene transcription. As transcriptional reprogramming is the molecular substrate of trained immunity, a de facto innate immune memory, we investigated the role of SIRT1 in the induction of trained immunity. We identified various SIRT1 genetic single nucleotide polymorphisms affecting innate and adaptive cytokine production of human peripheral blood mononuclear cells (PBMCs) in response to various stimuli on the one hand, and in vitro induction of trained immunity on the other hand. Furthermore, inhibition of SIRT1 upregulated pro-inflammatory innate cytokine production upon stimulation of PBMCs. However, inhibition of SIRT1 in vitro had no effect on cytokine responses upon induction of trained immunity, while activation of SIRT1 mildly modified trained immunity responses. In conclusion, SIRT1 modifies innate cytokine production by PBMCs in response to various microbes, but has only a secondary role for BCG and β-glucan-induced trained immunity responses.
    • Targeted T cell receptor gene editing provides predictable T cell product function for immunotherapy.

      Müller, Thomas R; Jarosch, Sebastian; Hammel, Monika; Leube, Justin; Grassmann, Simon; Bernard, Bettina; Effenberger, Manuel; Andrä, Immanuel; Chaudhry, M Zeeshan; Käuferle, Theresa; et al. (Elsevier, 2021-08-17)
      Adoptive transfer of T cells expressing a transgenic T cell receptor (TCR) has the potential to revolutionize immunotherapy of infectious diseases and cancer. However, the generation of defined TCR-transgenic T cell medicinal products with predictable in vivo function still poses a major challenge and limits broader and more successful application of this "living drug." Here, by studying 51 different TCRs, we show that conventional genetic engineering by viral transduction leads to variable TCR expression and functionality as a result of variable transgene copy numbers and untargeted transgene integration. In contrast, CRISPR/Cas9-mediated TCR replacement enables defined, targeted TCR transgene insertion into the TCR gene locus. Thereby, T cell products display more homogeneous TCR expression similar to physiological T cells. Importantly, increased T cell product homogeneity after targeted TCR gene editing correlates with predictable in vivo T cell responses, which represents a crucial aspect for clinical application in adoptive T cell immunotherapy.