•Bacteria adorn their surfaces with a variety of diverse glycan structures.•Protein glycosylation pathways involve block or sequential transfer of sugars.•Surface protein glycans may impact on ...motility, adhesion, and immune escape.
Bacterial surfaces are rich in glycoconjugates such as capsules, lipopolysaccharides, and peptidoglycans. The discovery of prokaryotic protein glycosylation systems has revealed that many bacteria also have the capacity to synthesise a diverse array of protein glycans, in some cases using novel strategies that differ from those of eukaryotes. Despite advances in our understanding of glycan biosynthesis and the proteins that are targets of glycosylation in bacteria, the roles of these modifications are relatively less well explored. We present an overview of bacterial protein glycosylation systems in bacteria that are relevant to human health, and discuss current evidence which indicates that glycosylation of proteins may impact upon fundamental processes such as bacterial motility, adhesion, and the modulation of immune responses.
Background Asthma is related to airway inflammation and oxidative stress. High levels of reactive oxygen and nitrogen species can induce cytotoxic DNA damage. Nevertheless, little is known about the ...possible role of allergen-induced DNA damage and DNA repair as modulators of asthma-associated pathology. Objective We sought to study DNA damage and DNA damage responses induced by house dust mite (HDM) in vivo and in vitro. Methods We measured DNA double-strand breaks (DSBs), DNA repair proteins, and apoptosis in an HDM-induced allergic asthma model and in lung samples from asthmatic patients. To study DNA repair, we treated mice with the DSB repair inhibitor NU7441. To study the direct DNA-damaging effect of HDM on human bronchial epithelial cells, we exposed BEAS-2B cells to HDM and measured DNA damage and reactive oxygen species levels. Results HDM challenge increased lung levels of oxidative damage to proteins (3-nitrotyrosine), lipids (8-isoprostane), and nucleic acid (8-oxoguanine). Immunohistochemical evidence for HDM-induced DNA DSBs was revealed by increased levels of the DSB marker γ Histone 2AX (H2AX) foci in bronchial epithelium. BEAS-2B cells exposed to HDM showed enhanced DNA damage, as measured by using the comet assay and γH2AX staining. In lung tissue from human patients with asthma, we observed increased levels of DNA repair proteins and apoptosis, as shown by caspase-3 cleavage, caspase-activated DNase levels, and terminal deoxynucleotidyl transferase–mediated dUTP nick end-labeling staining. Notably, NU7441 augmented DNA damage and cytokine production in the bronchial epithelium and apoptosis in the allergic airway, implicating DSBs as an underlying driver of asthma pathophysiology. Conclusion This work calls attention to reactive oxygen and nitrogen species and HDM-induced cytotoxicity and to a potential role for DNA repair as a modulator of asthma-associated pathophysiology.
Expression of type four pili (Tfp) is essential for virulence in Neisseria meningitidis . Pili mediate adhesion, bacterial aggregation, and DNA uptake. In N. meningitidis , the major pilin subunit is ...encoded by the pilE gene. In some strains, PilE is subject to phase and antigenic variation, which can alter Tfp properties and together offer a possible mechanism of immune escape. Pilin expression and antigenic variation can be modulated in response to environmental cues; however, the precise mechanisms of such regulation remain unclear. We identified a promoter in the pilE locus, 3′ of the pilE coding sequence, on the antisense (AS) strand which is conserved in meningococci. We show that this promoter directs transcription of an AS RNA that is expressed during specific growth phases and in response to salt stress. Furthermore, we demonstrate that the transcript encompasses sequences complementary to the entire pilE coding sequence and 5′ untranslated region. AS RNAs can regulate the gene on the sense strand by altering transcript stability or translation. However, by using Northern blotting, quantitative reverse transcription-PCR (RT-PCR), and Western blotting, we found no significant AS RNA-dependent changes in pilE transcript or protein level. Instead, our data indicate that the AS RNA influences pilin antigenic variation. This work provides further insights into the complex regulation of pilin expression and variation in pathogenic Neisseria . IMPORTANCE Pathogenic Neisseria spp. express type four pili (Tfp) which are important for adhesion, aggregation and transformation. Some strains of N. meningitidis are able to vary the sequence of the major subunit (PilE) of the Tfp. The mechanisms underlying this variation are not fully defined, but the process requires several noncoding elements that are found adjacent to the pilE gene. In this work, we identified a cis- encoded RNA antisense to pilE in N. meningitidis . By using Northern blotting and RT-PCR analysis, we found that the RNA is expressed in stationary phase or following salt stress. Our work also indicates that this RNA does not significantly affect pilE or pilin expression levels but instead appears to modulate pilin variation.
Myopericarditis is a rare complication of vaccination. However, there have been increasing reports of myopericarditis following COVID-19 vaccination, especially among adolescents and young adults. We ...aimed to characterise the incidence of myopericarditis following COVID-19 vaccination, and compare this with non-COVID-19 vaccination.
We did a systematic review and meta-analysis, searching four international databases from Jan 1, 1947, to Dec 31, 2021, for studies in English reporting on the incidence of myopericarditis following vaccination (the primary outcome). We included studies reporting on people in the general population who had myopericarditis in temporal relation to receiving vaccines, and excluded studies on a specific subpopulation of patients, non-human studies, and studies in which the number of doses was not reported. Random-effects meta-analyses (DerSimonian and Laird) were conducted, and the intra-study risk of bias (Joanna Briggs Institute checklist) and certainty of evidence (Grading of Recommendations, Assessment, Development and Evaluations approach) were assessed. We analysed the difference in incidence of myopericarditis among subpopulations, stratifying by the type of vaccine (COVID-19 vs non-COVID-19) and age group (adult vs paediatric). Among COVID-19 vaccinations, we examined the effect of the type of vaccine (mRNA or non-mRNA), sex, age, and dose on the incidence of myopericarditis. This study was registered with PROSPERO (CRD42021275477).
The overall incidence of myopericarditis from 22 studies (405 272 721 vaccine doses) was 33·3 cases (95% CI 15·3-72·6) per million vaccine doses, and did not differ significantly between people who received COVID-19 vaccines (18·2 10·9-30·3, 11 studies 395 361 933 doses, high certainty) and those who received non-COVID-19 vaccines (56·0 10·7-293·7, 11 studies 9 910 788 doses, moderate certainty, p=0·20). Compared with COVID-19 vaccination, the incidence of myopericarditis was significantly higher following smallpox vaccinations (132·1 81·3-214·6, p<0·0001) but was not significantly different after influenza vaccinations (1·3 0·0-884·1, p=0·43) or in studies reporting on various other non-smallpox vaccinations (57·0 1·1-3036·6, p=0·58). Among people who received COVID-19 vaccines, the incidence of myopericarditis was significantly higher in males (vs females), in people younger than 30 years (vs 30 years or older), after receiving an mRNA vaccine (vs non-mRNA vaccine), and after a second dose of vaccine (vs a first or third dose).
The overall risk of myopericarditis after receiving a COVID-19 vaccine is low. However, younger males have an increased incidence of myopericarditis, particularly after receiving mRNA vaccines. Nevertheless, the risks of such rare adverse events should be balanced against the risks of COVID-19 infection (including myopericarditis).
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The aim of this study is to investigate the blood flow pattern in carotid bifurcation with a high degree of luminal stenosis, combining in vivo magnetic resonance imaging (MRI) and computational ...fluid dynamics (CFD). A newly developed two-equation transitional model was employed to evaluate wall shear stress (WSS) distribution and pressure drop across the stenosis, which are closely related to plaque vulnerability. A patient with an 80% left carotid stenosis was imaged using high resolution MRI, from which a patient-specific geometry was reconstructed and flow boundary conditions were acquired for CFD simulation. A transitional model was implemented to investigate the flow velocity and WSS distribution in the patient-specific model. The peak time-averaged WSS value of approximately 73 Pa was predicted by the transitional flow model, and the regions of high WSS occurred at the throat of the stenosis. High oscillatory shear index values up to 0.50 were present in a helical flow pattern from the outer wall of the internal carotid artery immediately after the throat. This study shows the potential suitability of a transitional turbulent flow model in capturing the flow phenomena in severely stenosed carotid arteries using patient-specific MRI data and provides the basis for further investigation of the links between haemodynamic variables and plaque vulnerability. It may be useful in the future for risk assessment of patients with carotid disease.
Cholangiocarcinoma (CC) and hepatocellularcarcinoma (HCC) are two main forms of liver malignancies, which exhibit differences in drug response and prognosis. Immunohistotochemical staining for ...cytokeratin markers has been used to some success in the differential diagnosis of CC from HCC. However, there remains a need for additional markers for increased sensitivity and specificity of diagnosis. In this study, we have identified a p38 MAP kinase, p38δ (also known as MAPK13 or SAPK4) as a protein that is upregulated in CC relative to HCC and to normal biliary tract tissues. We performed microarray gene expression profiling on 17 cases of CC, 12 cases of adjacent normal liver tissue, and three case of normal bile duct tissue. p38δ was upregulated in 16 out of 17 cases of CC relative to normal tissue. We subsequently performed immunohistochemical staining of p38δ in 54 cases of CC and 54 cases of HCC. p38δ staining distinguished CC from HCC with a sensitivity of 92.6% and a specificity of 90.7%. To explore the possible functional significance of p38δ expression in CC, we examined the effects of overexpression and knockdown of p38δ expression in human CC cell lines. Our results indicate that p38δ is important for motility and invasion of CC cells, suggesting that p38δ may play an important role in CC metastasis. In summary, p38δ may serve as a novel diagnostic marker for CC and may also serve as a new target for molecular based therapy of this disease.
A woman in her 70s presented to the hospital being generally unwell 8 days following the first dose of the AstraZeneca COVID-19 vaccination. She was in stage III acute kidney injury (AKI) with ...hyperkalaemia and metabolic acidosis. Urinalysis showed haematoproteinuria. Renal immunology screen was negative. She subsequently underwent two renal biopsies. The second biopsy showed features consistent with acute tubulointerstitial nephritis. She was commenced on oral steroids, which led to marked improvement of her renal function.There are reasons why AKI can occur post vaccination such as prerenal AKI from reduced oral intake postvaccination due to feeling unwell or developing vomiting or diarrhoea. Intravenous fluids were given to this patient but with no meaningful improvement in renal function. She developed a possible reaction to the AstraZeneca COVID-19 vaccine, which led to AKI as supported by the interstitial inflammation and presence of eosinophils on renal biopsy.
During colonisation of the upper respiratory tract, bacteria are exposed to gradients of temperatures. Neisseria meningitidis is often present in the nasopharynx of healthy individuals, yet can ...occasionally cause severe disseminated disease. The meningococcus can evade the human complement system using a range of strategies that include recruitment of the negative complement regulator, factor H (CFH) via factor H binding protein (fHbp). We have shown previously that fHbp levels are influenced by the ambient temperature, with more fHbp produced at higher temperatures (i.e. at 37°C compared with 30°C). Here we further characterise the mechanisms underlying thermoregulation of fHbp, which occurs gradually over a physiologically relevant range of temperatures. We show that fHbp thermoregulation is not dependent on the promoters governing transcription of the bi- or mono-cistronic fHbp mRNA, or on meningococcal specific transcription factors. Instead, fHbp thermoregulation requires sequences located in the translated region of the mono-cistronic fHbp mRNA. Site-directed mutagenesis demonstrated that two anti-ribosomal binding sequences within the coding region of the fHbp transcript are involved in fHbp thermoregulation. Our results shed further light on mechanisms underlying the control of the production of this important virulence factor and vaccine antigen.
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