Changes in Soluble CD18 in Murine Autoimmune Arthritis and Rheumatoid Arthritis Reflect Disease Establishment and Treatment Response

Introduction

In rheumatoid arthritis (RA) immune activation and presence of autoantibodies may precede clinical onset of disease, and joint destruction can progress despite remission. However, the underlying temporal changes of such immune system abnormalities in the inflammatory response during treat-to-target strategies remain poorly understood. We have previously reported low levels of the soluble form of CD18 (sCD18) in plasma from patients with chronic RA and spondyloarthritis. Here, we study the changes of sCD18 before and during treatment of early RA and following arthritis induction in murine models of rheumatoid arthritis.

Methods

The level of sCD18 was analyzed with a time-resolved immunoflourometric assay in 1) plasma from early treatment naïve RA patients during a treat-to-target strategy (the OPERA cohort), 2) plasma from chronic RA patients, 3) serum from SKG and CIA mice following arthritis induction, and 4) supernatants from synovial fluid mononuclear cells (SFMCs) and peripheral blood mononuclear cells (PBMCs) from 6 RA patients cultured with TNFα or adalimumab.

Results

Plasma levels of sCD18 were decreased in chronic RA patients compared with early RA patients and in early RA patients compared with healthy controls. After 12 months of treatment the levels in early RA patients were similar to healthy controls. This normalization of plasma sCD18 levels was more pronounced in patients with very early disease who achieved an early ACR response. Plasma sCD18 levels were associated with radiographic progression. Correspondingly, the serum level of sCD18 was decreased in SKG mice 6 weeks after arthritis induction compared with healthy littermates. The sCD18 levels in both SKG and CIA mice exhibited a biphasic course after arthritis induction with an initial increase above baseline followed by a decline. Shedding of CD18 from RA SFMC and RA PBMC cultures was increased by TNFα and decreased by adalimumab.

Conclusions

The plasma sCD18 levels were altered in patients with RA, in mice with autoimmune arthritis and in cell cultures treated with TNFα and adalimumab. Decreased levels of plasma sCD18 could reflect autoimmunity in transition from early to chronic disease and normalization in response to treatment could reflect autoimmunity in remission.     

RNA interference-mediated inhibition of Semliki Forest virus replication in mammalian cells

RNA interference (RNAi) has recently shown promise as a mode of inhibition of slowly replicating viruses causing chronic diseases such as hepatitis C. To investigate whether RNAi is also feasible for rapidly growing RNA viruses such as alphaviruses, we tested the ability of expressed short hairpin RNAs (shRNAs) to inhibit the Semliki Forest virus (SFV), a rapidly replicating positive-strand RNA virus. Plasmids expressing shRNAs targeting SFV target sequences under the control of a human U6 promoter were introduced into BHK-21 cells. The targets included sequences encoding nonstructural (nsP1, 2, and 4) and structural (capsid) proteins as well as nonviral sequences serving as control targets. Twenty-four to 48 hours following transfection with shRNA plasmids, the cells were infected with replication-competent or replication-deficient recombinant SFV expressing green fluorescent protein (GFP) at a multiplicity of infection (MOI) of approximately 5. Viral replication was monitored by fluorescence microscopy and flow cytometry. Specific and marked reduction of viral replication was observed with shRNAs targeting nsP1 and nsP4. The degree of inhibition of the replication-deficient SFV was >or=70% over a 5-day period, a level similar to the transfection efficiency, suggesting complete inhibition of nonreplicating virus in the transfected cell population. However, only nsP1 shRNA was inhibitory against replication-competent SFV (approximately 30%-50% reduction), and this effect was transient. No inhibition was observed with control shRNAs. In contrast to the recent success of RNAi approaches for slowly growing viruses, these results illustrate the challenge of inhibiting very rapidly replicating RNA viruses by RNAi. However, the addition of RNAi approaches to other antiviral modalities might improve the response to acute infections.     

The effect of hydraulic retention time on the performance and fouling characteristics of membrane sequencing batch reactors used for the treatment of synthetic petroleum refinery wastewater

The use of membrane sequencing batch reactors, operated at HRT of 8, 16 and 24 h, was considered for the treatment of a synthetic petroleum wastewater. Increase in HRT resulted in statistically significant decrease in MLSS. Removal efficiencies higher than 97% were found for the three model hydrocarbon pollutants at all HRTs, with air stripping making a small contribution to overall removal. Particle size distribution (PSD) and microscopic analysis showed reduction in the protozoan populations in the activated sludge with decreasing HRT. PSD analysis also showed a higher proportion of larger and smaller sized particles at the lowest HRT. The rate of membrane fouling was found to increase with decreasing HRT; SMP, especially carbohydrate SMP, and mixed liquor apparent viscosity also showed a pronounced increase with decreasing HRT, whereas the concentration of EPS and its components decreased. FTIR analysis identified organic compounds as the main component of membrane pore fouling.     

Na‐Ion Intercalation and Charge Storage Mechanism in 2D Vanadium Carbide

2D vanadium carbide MXene containing surface functional groups (denoted as V₂CT_x , where T_x are surface functional groups) is synthesized and studied as anode material for Na‐ion batteries. V₂CT_x anode exhibits reversible charge storage with good cycling stability and high rate capability through electrochemical test. The charge storage mechanism of V₂CT_x material during Na⁺ intercalation/deintercalation and the redox reaction of vanadium are studied using a combination of synchrotron based X‐ray diffraction, hard X‐ray absorption near edge spectroscopy (XANES), and soft X‐ray absorption spectroscopy (sXAS). Experimental evidence of a major contribution of redox reaction of vanadium to the charge storage and the reversible capacity of V₂CT_x during sodiation/desodiation process are provided through V K ‐edge XANES and V L _2,3‐edge sXAS results. A correlation between the CO₃^2? content and the Na⁺ intercalation/deintercalation states in the V₂CT_x electrode observed from C and O K ‐edge in sXAS results implies that some additional charge storage reactions may take place between the Na⁺‐intercalated V₂CT_x and the carbonate‐based nonaqueous electrolyte. The results of this study provide valuable information for the further studies on V₂CT_x as anode material for Na‐ion batteries and capacitors.     

Selectivity of labeled bromoethylamine for protein alkylation

Alkylation of cysteine residues has been used extensively for characterization of proteins and their mode of action in biological systems, research endeavors that are at the core of proteomics. Treatment with a simple alkylating agent such as [2-(13)C] bromoethylamine would result in labeled thialysine at the ε-position. This chemical modification of proteins would allow investigations via both (13)C NMR spectroscopy and mass spectrometry. However [2-(13)C] labeled bromoethylamine is not available commercially. We investigated its synthesis at acid pH with the goal of obtaining singly labeled bromoethylamine and understanding the mechanistic details of the reaction. Based on our experimental and theoretical results, bromination of [2-(13)C] labeled ethanolamine in acidic conditions takes place via exclusive attack of the nucleophile (HBr) at the hydroxyl bearing C. Moreover, hydrogen bonding guides the nucleophilic attack, resulting in no label scrambling of the bromoethylamine product. Protein alkylation at cysteine residue with the synthesized Br(13)CH(2)CH(2)NH(2)-HBr is successful. Ab initio calculations in which CH(3)SH serves as a model for the cysteine residue suggest that in gas phase intermolecular attack by the sulfur bearing nucleophile is favored over the intramolecular substitution by the amino group by 15.4?kJ?mol(-1). Solution modeling shows that the trend is preserved at basic pH, which is the experimental one, but is reversed at neutral pH.     

Functional coordination of alternative splicing in the mammalian central nervous system

Background

Alternative splicing (AS) functions to expand proteomic complexity and plays numerous important roles in gene regulation. However, the extent to which AS coordinates functions in a cell and tissue type specific manner is not known. Moreover, the sequence code that underlies cell and tissue type specific regulation of AS is poorly understood.

Results

Using quantitative AS microarray profiling, we have identified a large number of widely expressed mouse genes that contain single or coordinated pairs of alternative exons that are spliced in a tissue regulated fashion. The majority of these AS events display differential regulation in central nervous system (CNS) tissues. Approximately half of the corresponding genes have neural specific functions and operate in common processes and interconnected pathways. Differential regulation of AS in the CNS tissues correlates strongly with a set of mostly new motifs that are predominantly located in the intron and constitutive exon sequences neighboring CNS-regulated alternative exons. Different subsets of these motifs are correlated with either increased inclusion or increased exclusion of alternative exons in CNS tissues, relative to the other profiled tissues.

Conclusion

Our findings provide new evidence that specific cellular processes in the mammalian CNS are coordinated at the level of AS, and that a complex splicing code underlies CNS specific AS regulation. This code appears to comprise many new motifs, some of which are located in the constitutive exons neighboring regulated alternative exons. These data provide a basis for understanding the molecular mechanisms by which the tissue specific functions of widely expressed genes are coordinated at the level of AS.     

Human mobility patterns predict divergent epidemic dynamics among cities

The epidemic dynamics of infectious diseases vary among cities, but it is unclear how this is caused by patterns of infectious contact among individuals. Here, we ask whether systematic differences in human mobility patterns are sufficient to cause inter-city variation in epidemic dynamics for infectious diseases spread by casual contact between hosts. We analyse census data on the mobility patterns of every full-time worker in 48 Canadian cities, finding a power-law relationship between population size and the level of organization in mobility patterns, where in larger cities, a greater fraction of workers travel to work in a few focal locations. Similarly sized cities also vary in the level of organization in their mobility patterns, equivalent on average to the variation expected from a 2.64-fold change in population size. Systematic variation in mobility patterns is sufficient to cause significant differences among cities in infectious disease dynamics—even among cities of the same size—according to an individual-based model of airborne pathogen transmission parametrized with the mobility data. This suggests that differences among cities in host contact patterns are sufficient to drive differences in infectious disease dynamics and provides a framework for testing the effects of host mobility patterns in city-level disease data.