Persistence of Epstein-Barr Virus in Self-Reactive Memory B Cells

Epstein-Barr virus infection has been epidemiologically associated with the development of multiple autoimmune diseases, particularly systemic lupus erythematosus and multiple sclerosis. Currently, there is no known mechanism that can account for these associations. The germinal-center (GC) model of EBV infection and persistence proposes that EBV gains access to the memory B cell compartment via GC reactions by driving infected cells to differentiate using the virus-encoded LMP1 and LMP2a proteins, which act as functional homologues of CD40 and the B cell receptor, respectively. The ability of LMP2a, when expressed in mice, to allow escape of autoreactive B cells suggests that it could perform a similar role in infected GC B cells, permitting the survival of potentially pathogenic autoreactive B cells. To test this hypothesis, we cloned and expressed antibodies from EBV⁺ and EBV⁻ memory B cells present during acute infection and profiled their self- and polyreactivity. We find that EBV does persist within self- and polyreactive B cells but find no evidence that it favors the survival of pathogenic autoreactive B cells. On the contrary, EBV⁺ memory B cells express lower levels of self-reactive and especially polyreactive antibodies than their uninfected counterparts do. Our work suggests that EBV has only a modest effect on the GC process, which allows it to access and persist within a subtly unique niche of the memory compartment characterized by relatively low levels of self- and polyreactivity. We suggest that this might reflect an active process where EBV and its human host have coevolved so as to minimize the virus''s potential to contribute to autoimmune disease.     

Left Ventricular Dysfunction and CXCR3 Ligands in Hypertension: From Animal Experiments to a Population-Based Pilot Study

Detecting left ventricular (LV) dysfunction at an early stage is key in addressing the heart failure epidemic. In proteome profiling experiments in mice subjected either to aortic banding or sham, the circulating CXCR3 ligands monokine induced by interferon-γ (MIG) and interferon-γ inducible protein 10 (IP10) were 5 to 40 fold up-regulated at eight weeks. We assessed the diagnostic value of circulating NT-pro BNP and CXCR3 ligands (MIG, IP10, Interferon-inducible T-cell alpha chemo-attractant [I–TAC]) in patients with hypertension (≥140/90 mm Hg) associated with subclinical (n = 19) or symptomatic (n = 16) diastolic LV dysfunction on echocardiography and healthy controls. NT–pro BNP, MIG, IP10, I–TAC all increased (p ≤ 0.014) across the categories of worsening left ventricular dysfunction. In patients with symptomatic disease, MIG, IP10, and I–TAC increased 210% (p = 0.015), 140% (p = 0.007) and 120% (p = 0.035) more than NT-pro BNP. The optimal discrimination limits, obtained by maximizing Youden’s index were 246 pmol/L, 65 pg/mL, 93 pg/mL, and 24 pg/mL, respectively. The odds ratios associated with the four biomarkers were significant (p ≤ 0.010), ranging from 4.00 for IP10 to 9.69 for MIG. With adjustment for NT–pro BNP, the CXCR3 ligands retained significance (p ≤ 0.028). Adding optimized thresholds for the CXCR3 ligands to NT–pro BNP enhanced (p ≤ 0.014) the integrated discrimination improvement and the net reclassification improvement. In conclusion, congruent with the concept that inflammation plays a key role in the pathogenesis of LV dysfunction, MIG, IP10 and I–TAC add diagnostic accuracy over and beyond NT–pro BNP.     

Physiographic and climatic events in the Chihuahuan Desert lead to the speciation and distinct demographic patterns of two sister Sceloporus lizards

The biogeographic history of the Chihuahuan Desert is known to be complex, and there is evidence of the effects of physiographic and climatic events in species diversification and demographic population changes in many taxa. Here, using DNA sequence data, we studied the influence of the physiographic and climatic events that occurred in the Chihuahuan Desert during the Pliocene–Pleistocene transition on the speciation and evolutionary history of the sister lizard species Sceloporus cyanostictus and S. gadsdeni. First, based on mtDNA and nDNA sequences, we estimated the divergence times of the sister species. Then, based on mtDNA sequences, we investigated the demographic history of both species within a phylogeographic framework. The divergence time was inferred to be 1.48 Mya, date that corresponds to the existence of a large lake in the Mapimian subprovince, between the current geographic locations of S. cyanostictus and S. gadsdeni. This lake could have acted as a barrier, leading to the speciation of both species. For the demographic history of the two species, we identified two distinct patterns: the population expansion of S. gadsdeni within the Last Glacial Maximum and the potential population decline of S. cyanostictus. Our results can be used as a guide for the study of other aspects that could be critical to developing conservation actions that ensure the survival of not only S. gadsdeni and S. cyanostictus, but also other co‐occurring lizard species.     

The Cytoprotective Effects of E-α-(4-Methoxyphenyl)-2’,3,4,4'-Tetramethoxychalcone (E-α-p-OMe-C6H4-TMC)—A Novel and Non-Cytotoxic HO-1 Inducer

Cell protection against different noxious stimuli like oxidative stress or chemical toxins plays a central role in the treatment of many diseases. The inducible heme oxygenase isoform, heme oxygenase-1 (HO-1), is known to protect cells against a variety of harmful conditions including apoptosis. Because a number of medium strong electrophiles from a series of α-X-substituted 2’,3,4,4’-tetramethoxychalcones (α-X-TMCs, X = H, F, Cl, Br, I, CN, Me, p-NO₂-C₆H₄, Ph, p-OMe-C₆H₄, NO₂, CF₃, COOEt, COOH) had proven to activate Nrf2 resulting in HO-1 induction and inhibit NF-κB downstream target genes, their protective effect against staurosporine induced apoptosis and reactive oxygen species (ROS) production was investigated. RAW264.7 macrophages treated with 19 different chalcones (15 α-X-TMCs, chalcone, 2’-hydroxychalcone, calythropsin and 2’-hydroxy-3,4,4’-trimethoxychalcone) prior to staurosporine treatment were analyzed for apoptosis and ROS production, as well as HO-1 protein expression and enzyme activity. Additionally, Nrf2 and NF-κB activity was assessed. We found that amongst all tested chalcones only E-α-(4-methoxyphenyl)-2’,3,4,4''-tetramethoxychalcone (E-α-p-OMe-C₆H₄-TMC) demonstrated a distinct, statistically significant antiapoptotic effect in a dose dependent manner, showing no toxic effects, while its double bond isomer Z-α-p-OMe-C₆H₄-TMC displayed no significant activity. Also, E-α-p-OMe-C₆H₄-TMC induced HO-1 protein expression and increased HO-1 activity, whilst inhibition of HO-1 by SnPP-IX abolished its antiapoptotic effect. The only weakly electrophilic chalcone E-α-p-OMe-C₆H₄-TMC reduced the staurosporine triggered formation of ROS, while inducing the translocation of Nrf2 into the nucleus. Furthermore, staurosporine induced NF-κB activity was attenuated following E-α-p-OMe-C₆H₄-TMC treatment. Overall, E-α-p-OMe-C₆H₄-TMC demonstrated its effective cytoprotective potential via a non-toxic induction of HO-1 in RAW264.7 macrophages. The observed cytoprotective effect may partly be related to both, the activation of the Nrf2- and inhibition of the NF-κB pathway.     

Mouse Invariant Monoclonal Antibody NKT14: A Novel Tool to Manipulate iNKT Cell Function In Vivo

Invariant Natural Killer T (iNKT) cells are a T cell subset expressing an invariant T Cell Receptor (TCR) that recognizes glycolipid antigens rather than peptides. The cells have both innate-like rapid cytokine release, and adaptive-like thymic positive selection. iNKT cell activation has been implicated in the pathogenesis of allergic asthma and inflammatory diseases, while reduced iNKT cell activation promotes infectious disease, cancer and certain autoimmune diseases such as Type 1 diabetes (T1D). Therapeutic means to reduce or deplete iNKT cells could treat inflammatory diseases, while approaches to promote their activation may have potential in certain infectious diseases, cancer or autoimmunity. Thus, we developed invariant TCR-specific monoclonal antibodies to better understand the role of iNKT cells in disease. We report here the first monoclonal antibodies specific for the mouse invariant TCR that by modifying the Fc construct can specifically deplete or activate iNKT cells in vivo in otherwise fully immuno-competent animals. We have used both the depleting and activating version of the antibody in the NOD model of T1D. As demonstrated previously using genetically iNKT cell deficient NOD mice, and in studies of glycolipid antigen activated iNKT cells in standard NOD mice, we found that antibody mediated depletion or activation of iNKT cells respectively accelerated and retarded T1D onset. In BALB/c mice, ovalbumin (OVA) mediated airway hyper-reactivity (AHR) was abrogated with iNKT cell depletion prior to OVA sensitization, confirming studies in knockout mice. Depletion of iNKT cells after sensitization had no effect on AHR in the conducting airways but did reduce AHR in the lung periphery. This result raises caution in the interpretation of studies that use animals that are genetically iNKT cell deficient from birth. These activating and depleting antibodies provide a novel tool to assess the therapeutic potential of iNKT cell manipulation.     

Regeneration of a Gentiana pneumonanthe population in an oligotrophic wet meadow

Abstract. The aim of this study was to evaluate the critical phases of the life cycle of Gentiana pneumonanthe, the marsh gentian, a threatened species of the Bohemian flora. The effect of various conditions on germination and seedling establishment and the possible effect of competition on the performance of the species were tested. Seeds were sown in plots which were subjected to four treatments in a randomized complete blocks experiment: unmanaged meadow, mown meadow, burned meadow, and meadow with cut sod. The significantly highest recruitment was found in plots with cut sod, the lowest in the unmanaged control plots. Seedling survival also differed among the treatments. In the following year surviving individuals were only found in plots with cut sod. The influence of neighbouring vegetation on target gentian individuals was evaluated by removing the surrounding vegetation and comparing the performance of these individuals with controls. The initial height of each individual was measured and used as a covariable. No significant effect of neighbouring vegetation on performance was detected. Thus, the establishment phase appears to be critical for population persistence and is also more influenced by the management regime than other stages of the life cycle.