Role of IFN-gamma and IL-6 in a protective immune response to Yersinia enterocolitica in mice

<p>Abstract</p> <p>Background</p> <p><it>Yersinia </it>outer protein (Yop) H is a secreted virulence factor of <it>Yersinia enterocolitica </it>(Ye), which inhibits phagocytosis of Ye and contributes to the virulence of Ye in mice. The aim of this study was to address whether and how YopH affects the innate immune response to Ye in mice.</p> <p>Results</p> <p>For this purpose, mice were infected with wild type Ye (pYV⁺) or a YopH-deficient Ye mutant strain (Δ<it>yopH</it>). CD11b⁺cells were isolated from the infected spleen and subjected to gene expression analysis using microarrays. Despite the attenuation of Δ<it>yopH in vivo</it>, by variation of infection doses we were able to achieve conditions that allow comparison of gene expression in pYV⁺and Δ<it>yopH </it>infection, using either comparable infection courses or splenic bacterial burden. Gene expression analysis provided evidence that expression levels of several immune response genes, including IFN-γ and IL-6, are high after pYV⁺infection but low after sublethal Δ<it>yopH </it>infection. In line with these findings, infection of IFN-γR^-/-and IL-6^-/-mice with pYV⁺or Δ<it>yopH </it>revealed that these cytokines are not necessarily required for control of Δ<it>yopH</it>, but are essential for defense against infection with the more virulent pYV⁺. Consistently, IFN-γ pretreatment of bone marrow derived macrophages (BMDM) strongly enhanced their ability in killing intracellular Ye bacteria.</p> <p>Conclusion</p> <p>In conclusion, this data suggests that IFN-γ-mediated effector mechanisms can partially compensate virulence exerted by YopH. These results shed new light on the protective role of IFN-γ in Ye wild type infections.</p

Multicentric Evaluation of SeeGene Allplex Real-Time PCR Assays Targeting 28 Bacterial, Microsporidal and Parasitic Nucleic Acid Sequences in Human Stool Samples

Prior to the implementation of new diagnostic techniques, a thorough evaluation is mandatory in order to ensure diagnostic reliability. If positive samples are scarcely available, however, such evaluations can be difficult to perform. Here, we evaluated four SeeGene Allplex real-time PCR assays amplifying a total of 28 bacteria, microsporidal and parasitic nucleic acid sequence targets in human stool samples in a multicentric approach. In the assessments with strongly positive samples, sensitivity values ranging between 13% and 100% were recorded for bacteria, between 0% and 100% for protozoa and between 7% and 100% for helminths and microsporidia; for the weakly positive samples, the recorded sensitivity values for bacteria ranged from 0% to 100%; for protozoa, from 0% to 40%; and for helminths and microsporidia, from 0% to 53%. For bacteria, the recorded specificity was in the range between 87% and 100%, while a specificity of 100% was recorded for all assessed PCRs targeting parasites and microsporidia. The intra- and inter-assay variations were generally low. Specifically for some helminth species, the sensitivity could be drastically increased by applying manual nucleic acid extraction instead of the manufacturer-recommended automatic procedure, while such effects were less obvious for the bacteria and protozoa. In summary, the testing with the chosen positive control samples showed varying degrees of discordance between the evaluated Allplex assays and the applied in-house reference assays associated with higher cycle threshold values in the Allplex assays, suggesting that samples with very low pathogen densities might be missed. As the targeted species can occur as harmless colonizers in the gut of individuals in high-endemicity settings as well, future studies should aim at assessing the clinical relevance of the latter hint.Peer Reviewe

Recurrence of chronic subdural hematoma due to low-grade infection

Despite the high incidence and multitudes of operative techniques, the risk factors for chronic subdural hematoma (CSDH) recurrence are still under debate and a universal consensus on the pathophysiology is lacking. We hypothesized that clinically inapparent, a low-grade infection could be responsible for CSDH recurrence. This investigation is a single-center prospective observational study including patients with recurrent CSDH. In total, 44 patients with CSDH recurrence received an intraoperative swab-based microbiological test. The intraoperative swab revealed an inapparent low-grade hematoma infection in 29% of the recurrent CSDH cases. The majority (69%) of the identified germs belonged to the staphylococcus genus. We therefore, propose a novel potential pathophysiology for CSDH recurrence

New pathogen-specific immunoPET/MR tracer for molecular imaging of a systemic bacterial infection

PublishedArticleThe specific and rapid detection of Enterobacteriaceae, the most frequent cause of gram-negative bacterial infections in humans, remains a major challenge. We developed a non-invasive method to rapidly detect systemic Yersinia enterocolitica infections using immunoPET (antibody-targeted positron emission tomography) with [64Cu]NODAGA-labeled Yersinia-specific polyclonal antibodies targeting the outer membrane protein YadA. In contrast to the tracer [18F]FDG, [64Cu]NODAGA-YadA uptake co-localized in a dose dependent manner with bacterial lesions of Yersinia-infected mice, as detected by magnetic resonance (MR) imaging. This was accompanied by elevated uptake of [64Cu]NODAGA-YadA in infected tissues, in ex vivo biodistribution studies, whereas reduced uptake was observed following blocking with unlabeled anti-YadA antibody. We show, for the first time, a bacteria-specific, antibody-based, in vivo imaging method for the diagnosis of a Gram-negative enterobacterial infection as a proof of concept, which may provide new insights into pathogen-host interactions.The research leading to these results has received funding from the European Union Seventh Framework Program (FP7/2007-2013) under grant agreement n°602820, from the European Social Fund Baden-Württemberg (to SEA), and from the Deutsche Forschungsgemeinschaft (grant WI 3777/1-2; to SW)

Physical activity is related to disease severity and fatigue, but not to relapse rate in persons with relapsing remitting multiple sclerosis – a self-reported questionnaire based study

IntroductionBased on theoretical models, physical activity has been introduced as a promoting method to mitigate the disease severity, fatigue and relapse rate in multiple sclerosis. The primary objective of the study was to investigate the relation between self-reported physical activity level and disease severity, fatigue and relapse rate in persons with relapsing remitting multiple sclerosis (RRMS).MethodsA survey was offered to persons with RRMS from March 2019 to August 2021 (n = 253). Physical activity level, fatigue and disease severity were determined using the Godin Leisure-Time Questionnaire (GLTEQ), the Patient Determined Disease Steps (PDDS) scale and the Fatigue Scale for Motor and Cognitive Functions (FSMC). Additionally, participants’ relapse rate was recorded.ResultsBivariate correlations revealed an inverse relation between physical activity level and PDDS (ρ = −0.279; p &lt; 0.001) as well as between physical activity and FSMC (r = −0.213, p &lt; 0.001), but not between physical activity and relapse rate (r = 0.033, p &gt; 0.05). Multiple linear regression analyses explained 12.6% and 5.2% of the variance of PDDS and FSMC.ConclusionOur findings confirm a relation between self-reported physical activity, disease severity and fatigue in persons with RRMS. However, self-reported physical activity level does not seem to affect the annualised relapse rate

Increased human defensine levels hint at an inflammatory etiology of bisphosphonate-associated osteonecrosis of the jaw: An immunohistological study

<p>Abstract</p> <p>Background</p> <p>Human β-defensins (hBD) are antimicrobial peptides that are an integral part of bone innate immunity. Recently, it could be shown that expression of hBD-1, -2 and -3 were upregulated in cases of osteomyelitis of the jaws. In order to gain insight into the possible impairment of hBD metabolism in bisphosphonate-associated osteonecrosis of the jaws (BONJ), the present exploratory study was designed so as to determine the qualitative and quantitative expression of afore mentioned hBDs in BONJ and infected osteoradionecrosis (ORN), both of which represent inflammatory bone diseases.</p> <p>Methods</p> <p>Bone samples were collected from patients with BONJ (n = 20) and ORN (n = 20). Non-infected healthy bone samples (n = 20) were included as controls. Immunohistological staining in an autostainer was carried out by the (Strept-ABC)-method against hBD-1,-2,-3. Specific positive vs. negative cell reaction of osteocytes (labeling index) near the border of bony resection was determined and counted for quantitative analysis. Number of vital osteocytes vs. empty osteocytes lacunae was compared between groups.</p> <p>Results</p> <p>hBD-1,-2 and -3 could be detected in BONJ as well as ORN and healthy bone samples. Immunoreactivity against hBD-2 and -3 was significantly higher in BONJ than in ORN and healthy jaw bone samples. Number of empty osteocyte lacunae was significantly higher in ORN compared with BONJ (<it>P </it>= 0.001).</p> <p>Conclusion</p> <p>Under the condition of BONJ an increased expression of hBD-1,-2,-3 is detectable, similarly to the recently described upregulation of defensins in chronically infected jaw bones. It remains still unclear how these findings may relate to the pathoetiology of these diseases and whether this is contributing to the development of BONJ and ORN or simply an after effect of the disease.</p

Immune Evasion by Yersinia enterocolitica: Differential Targeting of Dendritic Cell Subpopulations In Vivo

CD4+ T cells are essential for the control of Yersinia enterocolitica (Ye) infection in mice. Ye can inhibit dendritic cell (DC) antigen uptake and degradation, maturation and subsequently T-cell activation in vitro. Here we investigated the effects of Ye infection on splenic DCs and T-cell proliferation in an experimental mouse infection model. We found that OVA-specific CD4+ T cells had a reduced potential to proliferate when stimulated with OVA after infection with Ye compared to control mice. Additionally, proliferation of OVA-specific CD4+ T cells was markedly reduced when cultured with splenic CD8α+ DCs from Ye infected mice in the presence of OVA. In contrast, T-cell proliferation was not impaired in cultures with CD4+ or CD4−CD8α− DCs isolated from Ye infected mice. However, OVA uptake and degradation as well as cytokine production were impaired in CD8α+ DCs, but not in CD4+ and CD4−CD8α− DCs after Ye infection. Pathogenicity factors (Yops) from Ye were most frequently injected into CD8α+ DCs, resulting in less MHC class II and CD86 expression than on non-injected CD8α+ DCs. Three days post infection with Ye the number of splenic CD8α+ and CD4+ DCs was reduced by 50% and 90%, respectively. The decreased number of DC subsets, which was dependent on TLR4 and TRIF signaling, was the result of a faster proliferation and suppressed de novo DC generation. Together, we show that Ye infection negatively regulates the stimulatory capacity of some but not all splenic DC subpopulations in vivo. This leads to differential antigen uptake and degradation, cytokine production, cell loss, and cell death rates in various DC subpopulations. The data suggest that these effects might be caused directly by injection of Yops into DCs and indirectly by affecting the homeostasis of CD4+ and CD8α+ DCs. These events may contribute to reduced T-cell proliferation and immune evasion of Ye

Some Are More Equal - A Comparative Study on Swab Uptake and Release of Bacterial Suspensions

<div><p>Objectives</p><p>Swabs are widely used to collect samples for microbiological analyses from various clinical settings. They vary by material, size, and structure of the tip. This study investigates the uptake and release capacities for liquid and bacteria.</p><p>Methods</p><p>Five swabs were analyzed for their uptake and release capacities of S<i>taphylococcus aureus</i> and <i>Staphylococcus epidermidis</i> suspensions. Two approaches were investigated providing volume-restricted and unrestricted amounts of bacterial suspensions to mimic various clinical situations. Volume and bacterial uptake and release were measured in milligrams and by counting colony forming units (CFU), respectively.</p><p>Results</p><p>Volume uptake and release in the unrestricted setting varied highly significant between 239.6 mg and 88.7 mg (p<0.001) and between 65.2 mg and 2.2 mg (p<0.001), respectively. In the volume-restricted setting the complete volume was absorbed by all swabs, volume release could only be detected for flocked swabs (2.7 mg; p<0.001). Highest amount of CFU release was detected for the MWE Dryswab in the unrestricted setting for both <i>S. aureus</i> and <i>S. epidermidis</i> with 1544 CFU and 553 CFU, respectively, lowest release for the Sarstedt neutral swab with 32 CFU and 17 CFU, respectively (p<0.001). In the volume-restricted setting MWE Σ-Swab released the highest bacterial amount with 135 CFU <i>S. aureus</i> and 55 CFU <i>S. epidermidis</i>, respectively, the lowest amount was released by Mast Mastaswab with 2 CFU <i>S. aureus</i> and 1 CFU <i>S. epidermidis</i>, respectively (p<0.001). Within the range of the utilized bacterial concentrations, uptake/release ratios were identical for the particular swab types and independent of the bacterial species.</p><p>Conclusions</p><p>The influence of the swab type on subsequent diagnostic results is often underestimated. Uptake and release of the investigated bacteria vary significantly between different swab types and sampling conditions. For best diagnostic outcome swabs should be chosen according to the examined situation and the swab performance profile.</p></div