Neurological Complications in Systemic Inflammatory Diseases

Systemic inflammatory diseases could produce neurologic complications, and they are frequently incorporated in the differential diagnosis of neurological symptoms. There are wellestablished criteria to meet the diagnosis of neurologic manifestations of these systemic diseases. Methods: However, the range of clinical presentations varies in each condition, and the prevalence of these complications differs between studies. Hence, in many cases, an etiological relationship is not clearly defined. Results and Conclusion: For these reasons, it is challenging to make an accurate diagnosis. We analyzed the spectrum of neurological manifestations in a cohort of patients with systemic lupus erythematosus, rheumatoid arthritis, Behçet disease and sarcoidosis in order to improve our current knowledge of these complications.

Actin Assembly around the Shigella-Containing Vacuole Promotes Successful Infection

The enteroinvasive bacterium Shigella flexneri forces its uptake into non-phagocytic host cells through the translocation of T3SS effectors that subvert the actin cytoskeleton. Here, we report de novo actin polymerization after cellular entry around the bacterium-containing vacuole (BCV) leading to the formation of a dynamic actin cocoon. This cocoon is thicker than any described cellular actin structure and functions as a gatekeeper for the cytosolic access of the pathogen. Host CDC42, TOCA-1, N-WASP, WIP, the Arp2/3 complex, cortactin, coronin, and cofilin are recruited to the actin cocoon. They are subverted by T3SS effectors, such as IpgD, IpgB1, and IcsB. IcsB immobilizes components of the actin polymerization machinery at the BCV dependent on its fatty acyltransferase activity. This represents a unique microbial subversion strategy through localized entrapment of host actin regulators causing massive actin assembly. We propose that the cocoon promotes subsequent invasion steps for successful Shigella infection.

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A thick actin cocoon forms de novo around the Shigella-containing vacuole upon entry

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The effector IcsB entraps host actin regulators at the vacuole by lipidation

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Cdc42, N-WASP, and the Arp2/3 complex are major actin cocoon regulators

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Cocoon formation promotes subsequent Shigella niche formation and dissemination

The histone demethylase KDM6B fine-tunes the host response to Streptococcus pneumoniae

Streptococcus pneumoniae is a natural colonizer of the human respiratory tract and an opportunistic pathogen. Although epithelial cells are among the first to encounter pneumococci, the cellular processes and contribution of epithelial cells to the host response are poorly understood. Here, we show that a S. pneumoniae serotype 6B ST90 strain, which does not cause disease in a murine infection model, induces a unique NF-κB signature response distinct from an invasive-disease-causing isolate of serotype 4 (TIGR4). This signature is characterized by activation of p65 and requires a histone demethylase KDM6B. We show, molecularly, that the interaction of the 6B strain with epithelial cells leads to chromatin remodelling within the IL-11 promoter in a KDM6B-dependent manner, where KDM6B specifically demethylates histone H3 lysine 27 dimethyl. Remodelling of the IL-11 locus facilitates p65 access to three NF-κB sites that are otherwise inaccessible when stimulated by IL-1β or TIGR4. Finally, we demonstrate through chemical inhibition of KDM6B with GSK-J4 inhibitor and through exogenous addition of IL-11 that the host responses to the 6B ST90 and TIGR4 strains can be interchanged both in vitro and in a murine model of infection in vivo. Our studies therefore reveal how a chromatin modifier governs cellular responses during infection.

B Cell Development and T-Dependent Antibody Response Are Regulated by p38γ and p38δ

p38MAP kinase (MAPK) signal transduction pathways are important regulators of inflammation and the immune response; their involvement in immune cell development and function is still largely unknown. Here we analysed the role of the p38 MAPK isoforms p38γ and p38δ in B cell differentiation in bone marrow (BM) and spleen, using mice lacking p38γ and p38δ, or conditional knockout mice that lack both p38γ and p38δ specifically in the B cell compartment. We found that the B cell differentiation programme in the BM was not affected in p38γ/δ-deficient mice. Moreover, these mice had reduced numbers of peripheral B cells as well as altered marginal zone B cell differentiation in the spleen. Expression of co-stimulatory proteins and activation markers in p38γ/δ-deficient B cells are diminished in response to B cell receptor (BCR) and CD40 stimulation; p38γ and p38δ were necessary for B cell proliferation induced by BCR and CD40 but not by TLR4 signaling. Furthermore, p38γ/δ-null mice produced significantly lower antibody responses to T-dependent antigens. Our results identify unreported functions for p38γ and p38δ in B cells and in the T-dependent humoral response; and show that the combined activity of these kinases is needed for peripheral B cell differentiation and function.

Separating Actin-Dependent Chemokine Receptor Nanoclustering from Dimerization Indicates a Role for Clustering in CXCR4 Signaling and Function

A current challenge in cell motility studies is to understand the molecular and physical mechanisms that govern chemokine receptor nanoscale organization at the cell membrane, and their influence on cell response. Using single-particle tracking and super-resolution microscopy, we found that the chemokine receptor CXCR4 forms basal nanoclusters in resting T cells, whose extent, dynamics, and signaling strength are modulated by the orchestrated action of the actin cytoskeleton, the co-receptor CD4, and its ligand CXCL12. We identified three CXCR4 structural residues that are crucial for nanoclustering and generated an oligomerization-defective mutant that dimerized but did not form nanoclusters in response to CXCL12, which severely impaired signaling. Overall, our data provide new insights to the field of chemokine biology by showing that receptor dimerization in the absence of nanoclustering is unable to fully support CXCL12-mediated responses, including signaling and cell function in vivo.

Enhanced, robust light-driven H2 generation by gallium-doped titania nanoparticles

The splitting of water into molecular hydrogen and oxygen with the use of renewable solar energy is considered one of the most promising routes to yield sustainable fuel. Herein, we report the H₂ evolution performance of gallium doped TiO₂ photocatalysts with varying degrees of Ga dopant. The gallium(iii) ions induced significant changes in the structural, textural and electronic properties of TiO₂ nanoparticles, resulting in remarkably enhanced photocatalytic activity and good stability for H₂ production. Ga³⁺ ions can act as hole traps that enable a large number of excited electrons to migrate towards the TiO₂ surface, thereby facilitating electron transfer and charge separation. Additionally, the cationic dopant and its induced defects might introduce a mid-gap state, promoting electron migration and prolonging the lifetime of charge carrier pairs. We have discovered that the optimal Ga dopant concentration was 3.125 at% and that the incorporation of platinum (0.5 wt%) as a co-catalyst further improved the H₂ evolution rate up to 5722 μmol g^-1 h^-1. Pt not only acts as an electron sink, drastically increasing the electron/hole pair lifetime, but it also creates an intimate contact at the heterojunction between Pt and Ga-TiO₂, thus improving the interfacial electron transfer process. These catalyst design strategies provide new ways of designing transition metal photocatalysts that improve green fuel production from renewable solar energy and water.

Human adipose tissue-derived mesenchymal stromal cells promote B-cell motility and chemoattraction

BACKGROUND AIMS

Mesenchymal stromal cells hold special interest for cell-based therapy because of their tissue-regenerative and immunosuppressive abilities. B-cell involvement in chronic inflammatory and autoimmune pathologies makes them a desirable target for cell-based therapy. Mesenchymal stromal cells are able to regulate B-cell function; although the mechanisms are little known, they imply cell-to-cell contact.

METHODS

We studied the ability of human adipose tissue-derived mesenchymal stromal cells (ASCs) to attract B cells.

RESULTS

We show that ASCs promote B-cell migration through the secretion of chemotactic factors. Inflammatory/innate signals do not modify ASC capacity to mediate B-cell motility and chemotaxis. Analysis of a panel of B cell-related chemokines showed that none of them appeared to be responsible for B-cell motility. Other ASC-secreted factors able to promote cell motility and chemotaxis, such as the cytokine interleukin-8 and prostaglandin E2, did not appear to be implicated.

CONCLUSIONS

We propose that ASC promotion of B-cell migration by undefined secreted factors is crucial for ASC regulation of B-cell responses.

Flow cytometry analysis of Nosema species to assess spore viability and longevity

Nosema apis and Nosema ceranae are microsporidia which present resistant spores for the transmission stage (environmental spores) that play an important role for epidemiology and for laboratory studies of honey bee microsporidiosis. In this study, the long-term longevity of N. apis and N. ceranae spores exposed to 4 °C, room temperature (mean 25 °C) and 35 °C for 6-month long and to -20 °C for 10-month long has been assessed by flow cytometry. Storage temperature and the length of storage duration had adverse effects on spore viability of both Nosema spores, with significant differences between the two species. The greatest increase in spore mortality was observed in N. apis spores stored at 33 °C (64, 89%) and in N. ceranae spores at -20 °C (53.55%) and at 33 °C (51.97%). For N. ceranae spores at -20 °C, the loss in viability was very quick, getting an increase over 20% just after 6 days of exposure. Results on viability were confirmed by the infectivity tests where the lowest infectivity for N. ceranae was observed with spores stored for 10 months at -20 °C (79%; P < 0.05) and for N. apis with spores stored at 33 °C (71%; P < 0.05). For both Nosema species, the best storage temperatures were 25 and 4 °C, especially for N. apis that was almost unaffected at those temperatures.

Role of inflammasome-dependent cytokine production and neutrophil recruitment during acute lung injury that protects from Burkholderia species infection (55.17)

Burkholderia pseudomallei is a Gram-negative bacterium that infects macrophages and other cell types and causes melioidosis. We have recently shown that the Nod-like receptors (NLR) NLRP3 and NLRC4 differentially regulate pyroptosis and production of IL-1β and IL-18 in response to B. pseudomallei infection. Pyroptosis and IL-18 production were equally important for resistance to B. pseudomallei. Surprisingly, IL-1β was found to be deleterious in melioidosis. The detrimental role of IL-1β during melioidosis was due, in part, to excessive recruitment of neutrophils to the lung. We showed that neutrophils do not express NLRC4, fail to undergo pyroptosis, and, therefore, may be permissive to B. pseudomallei intracellular replication leading to increased bacterial burden and morbidity/mortality. Results will be presented to extended the analysis of the role of the inflammasome components NLRP3, NLRC4, ASC, and Caspase-1 and of IL-1β, IL-18, and pyroptosis during lung infection with other Burkholderia species like B. thailandensis and B. cepacia. Preliminary studies indicate that mice that underwent an acute lung injury (ALI) protocol showed an increased resistance to Burkholderia infection. We will show results that characterize the role of IFNγ and neutrophils recruitment in the protective effect of ALI.

Spectroscopic and DFT study of tungstic acid peroxocomplexes

The catalytic system formed by tungstic acid and its complexes with H2O2 and phenylphosphonic acid has been analyzed from the experimental and theoretical points of view. Previous structural studies by XRD proved the validity of the DFT proposed models and methodology. Hydrogen peroxide reacts with tungstic acid to form a peroxo complex. Vibrational and electronic spectra showed significant changes upon interaction with H2O2. The DFT and TD-DFT for IR and UV-vis calculations not only are in agreement with experimental data but also allow for a deeper characterization of the species formed in in situ conditions. A SCRF/PCM methodology was chosen to account for the solvent effect. The solvent effect of water was considered for geometry re-optimization of the structure and for the TD-DFT calculations.

A density functional theory study of the dissociation of H2 on gold clusters: Importance of fluxionality and ensemble effects

Density functional theory was employed to calculate the adsorption/dissociation of H2 on gold surfaces, Au(111) and Au(100), and on gold particles from 0.7 (Au14) to 1.2 nm (Au29). Flat surfaces of the bulk metal were not active towards H2, but a different effect was observed in gold nanoclusters, where the hydrogen was adsorbed through a dissociative pathway. Several parameters such as the coordination of the Au atoms, ensemble effects and fluxionality of the particle were analyzed to explain the observed activity. The effect of the employed functional was also studied. The flexibility of the structure, i.e., its adaptability towards the adsorbate, plays a key role in the bonding and dissociation of H2. The interaction with hydrogen leads to drastic changes in the structure of the Au nanoparticles. Furthermore, it appears that not only low coordinated Au atoms are needed because H2 adsorption/dissociation was only observed when a cooperation between several (4) active Au atoms was allowed.

Silylation and surface properties of chemically grafted hydrophobic silica

A commercial mesoporous silica (Grace Davison) was chemically grafted with trimethylsilyl chloride (TMSCl) and hexamethyldisilanaze (HMDS). The silylation process brought about some reduction in the specific BET area, the pore volume, and the pore sizes of the samples. Thermogravimetric studies of the silylated samples revealed that the grafting process is kinetically controlled at short reaction times. In the kinetic regime, increasing concentrations of the silylant agent up to 2 wt% in the solvent led to an increase of the extent of the silylated surface, although this limitation disappeared at higher concentrations. Silylation was confirmed by diffuse reflectance infrared Fourier transform (DRIFTS), (29)Si CP-MAS NMR, and photoelectron (XPS) spectroscopic techniques. Solid-state (29)Si MAS-NMR spectra of the silylated samples revealed the presence of -SiCH(3) groups (9.5 ppm) together with two resonances, Q3 (approximately equal to -104 ppm) and Q4 (approximately equal to -114 ppm), coming from siloxane [Qn approximately Si(OSi)n(OH)(4-n), n approximately 2-4] groups, the Q3 signal decreasing upon silylation. The DRIFT spectra of the silylated samples exhibited two well defined bands at 2970 and 2907 cm(-1), due to stretching vibration modes of the C-H bonds in surface -CH(3) groups formed during the silylation process, and also the disappearance of the band at 3740 cm(-1). This observation indicates the complete removal of terminal and geminal hydroxyl groups by grafting with the silylating agent. Similarly, high-resolution photoelectron spectra of the Si2p core levels showed a high binding-energy component (103.5 eV) in all the samples, coming from the Si coordinated with oxide anions in SiO(2), together with a second component at 102.1 eV, which is the fingerprint of Si coordinated by oxide anions and an organic group. Finally, the samples were ranked according to their hydrophobicity, as determined from the temperature-programmed desorption profiles of adsorbed water and 2-methylbutane.

Advances in Charcot-Marie-Tooth disease research: cellular function of CMT-related proteins, transgenic animal models, and pathomechanisms. The European CMT Consortium

The First Workshop of the European Consortium on Charcot-Marie-Tooth (CMT) disease brought together neuroscientists, molecular and cell biologists, neuropathologists, neurologists, and geneticists with a common interest in the understanding of the fundamental mechanisms that underlie the pathogenesis of CMT. The interdisciplinary group of 25 expert scientists discussed recent advances in (i) molecular genetics and histopathology of CMT, (ii) development of suitable animal models, (iii) understanding of the cellular function of CMT-related proteins, and (iv) studies using nerve biopsies from CMT patients. In this minireview, we summarize the key findings presented and discuss their impact on CMT research.

Modulation of pacemaker activity by IPSP and brief length perturbations in the crayfish stretch receptor

We have studied the influences of brief stretches and releases and of inhibitory postsynaptic potentials (IPSPs) on pacemaker activity of the crayfish stretch receptor (RM1). Stimuli shift or reset the ongoing rhythm. Resettings were different if evaluated in interspike intervals containing perturbations, or in succeeding ones, and are referred to as early and late, respectively. Early resetting revealed that stretches and releases or IPSPs advance and delay, respectively, the next spike. With small stretches and releases or IPSPs, effects depend on the timing of the perturbation relative to the previous spike or phase, but above a characteristic mechanical perturbation amplitude the next spike fires at a fixed latency, invariant with the phase. Of particular interest was the finding that during late resetting the first successive intervals following stretches and releases or IPSPs were longer and shorter, respectively, than the period. This led, in approximately 50% of the cases, to a gradual recovery of the original pacemaker beat in the sense that spikes fire timed as if the early rhythm shift had not occurred. In conclusion, the recent firing history is essential in determining the RM1's response. The receptor's sensitivity is a complex nonlinear and periodic function of the pacemaker activity, and the response is due to interactions between pacemaker- and perturbation-induced transmembrane ionic currents. Although several alternative mechanisms may underly beat recovery, the results suggest that at least two coupled oscillators, one perturbable and the other not, provide a better explanation than a single oscillator. The physiological significance of resettings is unknown, but the early rhythm shift may synchronize RM1s in several segments when the animal's tail is moved, and conversely recovery would reduce synchrony, with obvious influences on shared postsynaptic neurons.