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International Journal of Molecular... Nov 2023is a leading cause of nosocomial infections, particularly in immunocompromised patients. The rise of multidrug-resistant , including Vancomycin-Resistant Enterococci...
is a leading cause of nosocomial infections, particularly in immunocompromised patients. The rise of multidrug-resistant , including Vancomycin-Resistant Enterococci (VRE), is a major concern. Vaccines are promising alternatives to antibiotics, but there is currently no vaccine available against enterococci. In a previous study, we identified six protein vaccine candidates associated with extracellular membrane vesicles (MVs) produced by nosocomial . In this study, we immunized rabbits with two different VRE-derived MV preparations and characterized the resulting immune sera. Both anti-MV sera exhibited high immunoreactivity towards the homologous strain, three additional VRE strains, and eight different unrelated strains representing different sequence types (STs). Additionally, we demonstrated that the two anti-MV sera were able to mediate opsonophagocytic killing of not only the homologous strain but also three unrelated heterologous VRE strains. Altogether, our results indicate that MVs, regardless of the purification method for obtaining them, are promising vaccine candidates against multidrug-resistant and suggest that these naturally occurring MVs can be used as a multi-antigen platform to elicit protective immune responses against enterococcal infections.
Topics: Animals; Humans; Rabbits; Enterococcus faecalis; Anti-Bacterial Agents; Enterococcus faecium; Vancomycin-Resistant Enterococci; Vaccines; Gram-Positive Bacterial Infections; Microbial Sensitivity Tests
PubMed: 38003243
DOI: 10.3390/ijms242216051 -
Frontiers in Immunology 2023Autoimmune encephalitis (AE) is a distinct neuro-immunological disorder associated with the production of autoantibodies against neuronal proteins responsible for...
OBJECTIVE
Autoimmune encephalitis (AE) is a distinct neuro-immunological disorder associated with the production of autoantibodies against neuronal proteins responsible for pharmacoresistant seizures, cognitive decline and behavioral problems. To establish the causal link between leucine-rich glioma inactivated 1 (LGI1) antibody and seizures, we developed an antibody-mediated AE rat model in which serum antibodies (IgG) obtained from blood samples of leucine-rich glioma inactivated 1 (LGI1) protein antibody (IgG) positive encephalitis patients were passively transferred into non-epileptic Wistar rats. Serum IgG of N-methyl-d-aspartate receptor (NMDAR) antibody positive patients were used as positive control since the pathogenicity of this antibody has been previously shown in animal models.
METHODS
Total IgG obtained from the pooled sera of NMDAR and LGI1-IgG positive patients with epileptic seizures and healthy subjects was applied chronically every other day for 11 days into the cerebral lateral ventricle. Spontaneous seizure development was followed by electroencephalography. Behavioral tests for memory and locomotor activity were applied before and after the antibody infusions. Then, pentylenetetrazol (PTZ) was administered intraperitoneally to evaluate seizure susceptibility. Immunohistochemistry processed for assessment of hippocampal astrocyte proliferation and expression intensity of target NMDAR and LGI1 antigens.
RESULTS
No spontaneous activity was observed during the antibody infusions. PTZ-induced seizure stage was significantly higher in the NMDAR-IgG and LGI1-IgG groups compared to control. Besides, memory deficits were observed in the NMDAR and LGI1-IgG groups. We observed enhanced astrocyte proliferation in NMDAR- and LGI1-IgG groups and reduced hippocampal NMDAR expression in NMDAR-IgG group.
SIGNIFICANCE
These findings suggest that neuronal surface auto-antibody administration induces seizure susceptibility and disturbed cognitive performance in the passive transfer rat model of LGI1 AE, which could be a potential model for understanding immune-mediated mechanisms underlying epileptogenesis and highlight the potential targets for immune-mediated seizures in AE patients.
Topics: Humans; Rats; Animals; Leucine; Rats, Wistar; Encephalitis; Seizures; Autoantibodies; Epilepsy; Autoimmune Diseases of the Nervous System; Immunoglobulin G; Glioma; Cognition
PubMed: 38035091
DOI: 10.3389/fimmu.2023.1268986 -
MedRxiv : the Preprint Server For... Feb 2024Pregnancy is a risk factor for increased severity of SARS-CoV-2 and other respiratory infections. The mechanisms underlying this risk have not been well-established,...
Pregnancy is a risk factor for increased severity of SARS-CoV-2 and other respiratory infections. The mechanisms underlying this risk have not been well-established, partly due to a limited understanding of how pregnancy shapes immune responses. To gain insight into the role of pregnancy in modulating immune responses at steady state and upon perturbation, we collected peripheral blood mononuclear cells (PBMC), plasma, and stool from 226 women, including 152 pregnant individuals (n = 96 with SARS-CoV-2 infection and n = 56 healthy controls) and 74 non-pregnant women (n = 55 with SARS-CoV-2 and n = 19 healthy controls). We found that SARS-CoV-2 infection was associated with altered T cell responses in pregnant compared to non-pregnant women. Differences included a lower percentage of memory T cells, a distinct clonal expansion of CD4-expressing CD8 T cells, and the enhanced expression of T cell exhaustion markers, such as programmed cell death-1 (PD-1) and T cell immunoglobulin and mucin domain-3 (Tim-3), in pregnant women. We identified additional evidence of immune dysfunction in severely and critically ill pregnant women, including a lack of expected elevation in regulatory T cell (Treg) levels, diminished interferon responses, and profound suppression of monocyte function. Consistent with earlier data, we found maternal obesity was also associated with altered immune responses to SARS-CoV-2 infection, including enhanced production of inflammatory cytokines by T cells. Certain gut bacterial species were altered in pregnancy and upon SARS-CoV-2 infection in pregnant individuals compared to non-pregnant women. Shifts in cytokine and chemokine levels were also identified in the sera of pregnant individuals, most notably a robust increase of interleukin-27 (IL-27), a cytokine known to drive T cell exhaustion, in the pregnant uninfected control group compared to all non-pregnant groups. IL-27 levels were also significantly higher in uninfected pregnant controls compared to pregnant SARS-CoV-2-infected individuals. Using two different preclinical mouse models of inflammation-induced fetal demise and respiratory influenza viral infection, we found that enhanced IL-27 protects developing fetuses from maternal inflammation but renders adult female mice vulnerable to viral infection. These combined findings from human and murine studies reveal nuanced pregnancy-associated immune responses, suggesting mechanisms underlying the increased susceptibility of pregnant individuals to viral respiratory infections.
PubMed: 38370801
DOI: 10.1101/2024.02.05.24301794 -
Frontiers in Immunology 2023Scurfy mice have a complete deficiency of functional regulatory T cells (Treg) due to a frameshift mutation in the gene. The impaired immune homeostasis results in a...
INTRODUCTION
Scurfy mice have a complete deficiency of functional regulatory T cells (Treg) due to a frameshift mutation in the gene. The impaired immune homeostasis results in a lethal lymphoproliferative disorder affecting multiple organs, including the liver. The autoimmune pathology in scurfy mice is in part accompanied by autoantibodies such as antinuclear antibodies (ANA). ANA are serological hallmarks of several autoimmune disorders including autoimmune liver diseases (AILD). However, the underlying pathogenesis and the role of Treg in AILD remain to be elucidated. The present study therefore aimed to characterize the liver disease in scurfy mice.
METHODS
Sera from scurfy mice were screened for ANA by indirect immunofluorescence assay (IFA) and tested for a wide range of AILD-associated autoantibodies by enzyme-linked immunosorbent assay, line immunoassay, and addressable laser bead immunoassay. CD4 T cells of scurfy mice were transferred into T cell-deficient B6/nude mice. Monoclonal autoantibodies from scurfy mice and recipient B6/nude mice were tested for ANA by IFA. Liver tissue of scurfy mice was analyzed by conventional histology. Collagen deposition in scurfy liver was quantified via hepatic hydroxyproline content. Real-time quantitative PCR was used to determine fibrosis-related hepatic gene expression. Hepatic immune cells were differentiated by flow cytometry.
RESULTS
All scurfy mice produced ANA. AILD-associated autoantibodies, predominantly antimitochondrial antibodies, were detected at significantly higher levels in scurfy sera. CD4 T cells from scurfy mice were sufficient to induce anti-dsDNA autoantibodies and ANA with an AILD-related nuclear envelope staining pattern. Liver histology revealed portal inflammation with bile duct damage and proliferation, as in primary biliary cholangitis (PBC), and interface hepatitis with portal-parenchymal necroinflammation, as found in autoimmune hepatitis (AIH). In scurfy liver, TNFα and fibrosis-related transcripts including , and were upregulated. The level of proinflammatory monocytic macrophages (Ly-6C) was increased, while M2-type macrophages (CD206) were downregulated compared to wildtype controls. Despite severe hepatic inflammation, fibrosis did not develop within 25 days, which is close to the lifespan of scurfy mice.
DISCUSSION
Our findings suggest that Treg-deficient scurfy mice spontaneously develop clinical, serological, and immunopathological characteristics of AILD with overlapping features of PBC and AIH.
Topics: Mice; Animals; T-Lymphocytes, Regulatory; Mice, Nude; Autoantibodies; Hepatitis, Autoimmune; Liver Diseases; Fibrosis; Connective Tissue Diseases; Syndrome; Inflammation
PubMed: 37818371
DOI: 10.3389/fimmu.2023.1253649 -
MSphere Oct 2023Antibody responses to variant surface antigens (VSAs) produced by the malaria parasite may contribute to age-related natural immunity to severe malaria. One VSA family,...
Antibody responses to variant surface antigens (VSAs) produced by the malaria parasite may contribute to age-related natural immunity to severe malaria. One VSA family, erythrocyte membrane protein-1 (PfEMP1), includes a subset of proteins that binds endothelial protein C receptor (EPCR) in human hosts and potentially disrupts the regulation of inflammatory responses, which may lead to the development of severe malaria. We probed peptide microarrays containing segments spanning five PfEMP1 EPCR-binding domain variants with sera from 10 Malian adults and 10 children to determine the differences between adult and pediatric immune responses. We defined serorecognized peptides and amino acid residues as those that elicited a significantly higher antibody response than malaria-naïve controls. We aimed to identify regions consistently serorecognized among adults but not among children across PfEMP1 variants, potentially indicating regions that drive the development of immunity to severe malaria. Adult sera consistently demonstrated broader and more intense serologic responses to constitutive PfEMP1 peptides than pediatric sera, including peptides in EPCR-binding domains. Both adults and children serorecognized a significantly higher proportion of EPCR-binding peptides than peptides that do not directly participate in receptor binding, indicating a preferential development of serologic responses at functional residues. Over the course of a single malaria transmission season, pediatric serological responses increased between the start and the peak of the season, but waned as the transmission season ended. IMPORTANCE Severe malaria and death related to malaria disproportionately affect sub-Saharan children under 5 years of age, commonly manifesting as cerebral malaria and/or severe malarial anemia. In contrast, adults in malaria-endemic regions tend to experience asymptomatic or mild disease. Our findings indicate that natural immunity to malaria targets specific regions within the EPCR-binding domain, particularly peptides containing EPCR-binding residues. Epitopes containing these residues may be promising targets for vaccines or therapeutics directed against severe malaria. Our approach provides insight into the development of natural immunity to a binding target linked to severe malaria by characterizing an "adult-like" response as recognizing a proportion of epitopes within the PfEMP1 protein, particularly regions that mediate EPCR binding. This "adult-like" response likely requires multiple years of malaria exposure, as increases in pediatric serologic response over a single malaria transmission season do not appear significant.
Topics: Adult; Child; Humans; Child, Preschool; Endothelial Protein C Receptor; Protozoan Proteins; Malaria; Malaria, Falciparum; Epitopes; Peptides
PubMed: 37791774
DOI: 10.1128/msphere.00451-23 -
PloS One 2023Diagnostic immunoassays for Lyme disease have several limitations including: 1) not all patients seroconvert; 2) seroconversion occurs later than symptom onset; and 3)... (Observational Study)
Observational Study
BACKGROUND
Diagnostic immunoassays for Lyme disease have several limitations including: 1) not all patients seroconvert; 2) seroconversion occurs later than symptom onset; and 3) serum antibody levels remain elevated long after resolution of the infection.
INTRODUCTION
MENSA (Medium Enriched for Newly Synthesized Antibodies) is a novel diagnostic fluid that contains antibodies produced in vitro by circulating antibody-secreting cells (ASC). It enables measurement of the active humoral immune response.
METHODS
In this observational, case-control study, we developed the MicroB-plex Anti-C6/Anti-pepC10 Immunoassay to measure antibodies specific for the Borrelia burgdorferi peptide antigens C6 and pepC10 and validated it using a CDC serum sample collection. Then we examined serum and MENSA samples from 36 uninfected Control subjects and 12 Newly Diagnosed Lyme Disease Patients.
RESULTS
Among the CDC samples, antibodies against C6 and/or pepC10 were detected in all seropositive Lyme patients (8/8), but not in sera from seronegative patients or healthy controls (0/24). Serum antibodies against C6 and pepC10 were detected in one of 36 uninfected control subjects (1/36); none were detected in the corresponding MENSA samples (0/36). In samples from newly diagnosed patients, serum antibodies identified 8/12 patients; MENSA antibodies also detected 8/12 patients. The two measures agreed on six positive individuals and differed on four others. In combination, the serum and MENSA tests identified 10/12 early Lyme patients. Typically, serum antibodies persisted 80 days or longer while MENSA antibodies declined to baseline within 40 days of successful treatment.
DISCUSSION
MENSA-based immunoassays present a promising complement to serum immunoassays for diagnosis and tracking therapeutic success in Lyme infections.
Topics: Humans; Case-Control Studies; Antigens, Bacterial; Immunoglobulin G; Lyme Disease; Antibodies, Bacterial; Biomarkers; Antibody-Producing Cells; Early Diagnosis; Borrelia burgdorferi
PubMed: 37922270
DOI: 10.1371/journal.pone.0293203 -
Blood Advances Jul 2023Humoral antiplatelet factors, such as autoantibodies, are thought to primarily clear platelets by triggering macrophage phagocytosis in immune thrombocytopenia (ITP)....
Humoral antiplatelet factors, such as autoantibodies, are thought to primarily clear platelets by triggering macrophage phagocytosis in immune thrombocytopenia (ITP). However, there are few studies characterizing the capacity and mechanisms of humoral factor-triggered macrophage phagocytosis of platelets using specimens from patients with ITP. Here, we assessed sera from a cohort of 24 patients with ITP for the capacity to trigger macrophage phagocytosis of normal donor platelets and characterized the contribution of humoral factors to phagocytosis. Sera that produced a phagocytosis magnitude greater than a normal human serum mean + 2 standard deviations were considered phagocytosis-positive. Overall, 42% (8/19) of MHC I alloantibody-negative ITP sera were phagocytosis-positive. The indirect monoclonal antibody immobilization of platelet antigens assay was used to detect immunoglobulin G (IgG) autoantibodies to glycoproteins (GP)IIb/IIIa, GPIb/IX, and GPIa/IIa. Autoantibody-positive sera triggered a higher mean magnitude of phagocytosis than autoantibody-negative sera. Phagocytosis correlated inversely with platelet counts among autoantibody-positive patients but not among autoantibody-negative patients. Select phagocytosis-positive sera were separated into IgG-purified and -depleted fractions via protein G and reassessed for phagocytosis. Phagocytosis was largely retained in the purified IgG fractions. In addition, we assessed serum concentrations of C-reactive protein, serum amyloid P, and pentraxin 3 as potential phagocytosis modulators. Pentraxin 3 concentrations correlated inversely with platelet counts among patients positive for autoantibodies. Taken together, sera from approximately half of the patients with ITP studied triggered macrophage phagocytosis of platelets beyond a normal level. An important role for antiplatelet autoantibodies in phagocytosis is supported; a role for pentraxins such as pentraxin 3 may be suggested.
Topics: Humans; Purpura, Thrombocytopenic, Idiopathic; Blood Platelets; Thrombocytopenia; Platelet Glycoprotein GPIIb-IIIa Complex; Immunoglobulin G; Phagocytosis; Macrophages; Autoantibodies
PubMed: 37042934
DOI: 10.1182/bloodadvances.2022009423 -
BMJ Global Health Aug 2023Snakebite was added to the WHO neglected tropical disease (NTD) list in 2017, followed by a World Health Assembly resolution in 2018, and an explicit global target being...
BACKGROUND
Snakebite was added to the WHO neglected tropical disease (NTD) list in 2017, followed by a World Health Assembly resolution in 2018, and an explicit global target being set to reduce the burden in 2019. We aimed to understand how and why snakebite became a global health priority.
METHODS
We conducted a policy case study, using in-depth interviews, and documents (peer-reviewed and grey literature) as data sources. We drew on Shiffman 's framework on global health network to guide the analysis.
RESULTS
We conducted 20 interviews and examined 91 documents. The prioritisation of snakebite occurred in four phases: pre-crescendo, crescendo, de-crescendo and re-crescendo. The core snakebite network consisted of academics, which expanded during the re-crescendo phase to include civil society organisations and state actors. The involvement of diverse stakeholders led to better understanding of WHO processes. The use of intersecting and layered issue framing, framing solutions around snake antivenoms, in a background of cross-cultural fascination and fear of snakes enabled prioritisation in the re-crescendo phase. Ebbs and flows in legitimacy of the network and reluctant acceptance of snakebite within the NTD community are challenges.
CONCLUSION
Our analyses imply a fragile placement of snakebite in the global agenda. We identify two challenges, which needs to be overcome. The study highlights the need to review the WHO criteria for classifying diseases as NTD. We propose that future prioritisation analysis should consider identifying temporal patterns, as well as integrating legitimacy dimensions, as in our study.
Topics: Humans; Antivenins; Global Health; Health Priorities; Policy Making; Snake Bites; Animals
PubMed: 37604596
DOI: 10.1136/bmjgh-2023-011923 -
Frontiers in Immunology 2023Syphilis, a sexually transmitted infection caused by the spirochete (), is resurging globally. 's repertoire of outer membrane proteins (OMPs) includes BamA (β-barrel...
INTRODUCTION
Syphilis, a sexually transmitted infection caused by the spirochete (), is resurging globally. 's repertoire of outer membrane proteins (OMPs) includes BamA (β-barrel assembly machinery subunit A/TP0326), a bipartite protein consisting of a 16-stranded β-barrel with nine extracellular loops (ECLs) and five periplasmic POTRA (polypeptide transport-associated) domains. BamA ECL4 antisera promotes internalization of by rabbit peritoneal macrophages.
METHODS
Three overlapping BamA ECL4 peptides and a two-stage, phage display strategy, termed "Epivolve" (for epitope evolution) were employed to generate single-chain variable fragments (scFvs). Additionally, antisera generated by immunizing mice and rabbits with BamA ECL4 displayed by a thioredoxin scaffold (Trx). MAbs and antisera reactivities were evaluated by immunoblotting and ELISA. A comparison of murine and rabbit opsonophagocytosis assays was conducted to evaluate the functional ability of the Abs (, opsonization) and validate the mouse assay. Sera from -infected mice (MSS) and rabbits (IRS) were evaluated for ECL4-specific Abs using Trx and overlapping ECL4 peptides in immunoblotting and ELISA assays.
RESULTS
Each of the five mAbs demonstrated reactivity by immunoblotting and ELISA to nanogram amounts of Trx. One mAb, containing a unique amino acid sequence in both the light and heavy chains, showed activity in the murine opsonophagocytosis assay. Mice and rabbits hyperimmunized with Trx produced opsonic antisera that strongly recognized the ECL presented in a heterologous scaffold and overlapping ECL4 peptides, including S2. In contrast, Abs generated during infection of mice and rabbits poorly recognized the peptides, indicating that S2 contains a subdominant epitope.
DISCUSSION
Epivolve produced mAbs target subdominant opsonic epitopes in BamA ECL4, a top syphilis vaccine candidate. The murine opsonophagocytosis assay can serve as an alternative model to investigate the opsonic potential of vaccinogens. Detailed characterization of BamA ECL4-specific Abs provided a means to dissect Ab responses elicited by infection.
Topics: Mice; Animals; Rabbits; Treponema pallidum; Antibodies, Monoclonal; Syphilis; Immune Sera; Bacteriophages; Epitopes
PubMed: 37675118
DOI: 10.3389/fimmu.2023.1222267 -
NPJ Vaccines Oct 2023COVID-19 vaccines were originally designed based on the ancestral Spike protein, but immune escape of emergent Variants of Concern (VOC) jeopardized their efficacy,...
COVID-19 vaccines were originally designed based on the ancestral Spike protein, but immune escape of emergent Variants of Concern (VOC) jeopardized their efficacy, warranting variant-proof vaccines. Here, we used preclinical rodent models to establish the cross-protective and cross-neutralizing capacity of adenoviral-vectored vaccines expressing VOC-matched Spike. CoroVaxG.3-D.FR, matched to Delta Plus Spike, displayed the highest levels of nAb to the matched VOC and mismatched variants. Cross-protection against viral infection in aged K18-hACE2 mice showed dramatic differences among the different vaccines. While Delta-targeted vaccines fully protected mice from a challenge with Gamma, a Gamma-based vaccine offered only partial protection to Delta challenge. Administration of CorovaxG.3-D.FR in a prime/boost regimen showed that a booster was able to increase the neutralizing capacity of the sera against all variants and fully protect aged K18-hACE2 mice against Omicron BA.1, as a BA.1-targeted vaccine did. The neutralizing capacity of the sera diminished in all cases against Omicron BA.2 and BA.5. Altogether, the data demonstrate that a booster with a vaccine based on an antigenically distant variant, such as Delta or BA.1, has the potential to protect from a wider range of SARS-CoV-2 lineages, although careful surveillance of breakthrough infections will help to evaluate combination vaccines targeting antigenically divergent variants yet to emerge.
PubMed: 37794010
DOI: 10.1038/s41541-023-00737-4