10 research outputs found
Making the MUVE to virtual education
Second Life, a 3D multi-user virtual environment (MUVE), is becoming an increasingly popular topic at educational technology conferences and in the media these days. What’s all the fuss about
Autoreactivity to malondialdehyde-modifications in rheumatoid arthritis is linked to disease activity and synovial pathogenesis
Oxidation-associated malondialdehyde (MDA) modification of proteins can
generate immunogenic neo-epitopes that are recognized by autoantibodies. In
health, IgM antibodies to MDA-adducts are part of the natural antibody pool,
while elevated levels of IgG anti-MDA are associated with inflammatory
conditions. Yet, in human autoimmune disease IgG anti-MDA responses have not
been well characterized and their potential contribution to disease
pathogenesis is not known. Here, we investigate MDA-modifications and
anti-MDA-modified protein autoreactivity in rheumatoid arthritis (RA). While RA
is primarily associated with autoreactivity to citrullinated antigens, we also
observed increases in serum IgG anti-MDA in RA patients compared to controls.
IgG anti-MDA levels significantly correlated with disease activity by DAS28-ESR
and serum TNF-alpha, IL-6, and CRP. Mass spectrometry analysis of RA synovial
tissue identified MDA-modified proteins and revealed shared peptides between
MDA-modified and citrullinated actin and vimentin. Furthermore, anti-MDA
autoreactivity among synovial B cells was discovered when investigating
recombinant monoclonal antibodies (mAbs) cloned from single B cells. Several
clones were highly specific for MDA-modification with no cross-reactivity to
other antigen modifications. The mAbs recognized MDA-adducts in a variety of
proteins. Interestingly, the most reactive clone, originated from an
IgG1-bearing memory B cell, was encoded by germline variable genes, and showed
similarity to previously reported natural IgM. Other anti-MDA clones display
somatic hypermutations and lower reactivity. These anti-MDA antibodies had
significant in vitro functional properties and induced enhanced
osteoclastogenesis, while the natural antibody related high-reactivity clone
did not. We postulate that these may represent distinctly different facets of
anti-MDA autoreactive responses
Anticitrullinated protein antibodies facilitate migration of synovial tissue-derived fibroblasts
OBJECTIVES
Rheumatoid arthritis (RA)-specific anti-citrullinated protein/peptide antibodies (ACPAs) might contribute to bone loss and arthralgia before the onset of joint inflammation. We aimed to dissect additional mechanisms by which ACPAs might contribute to development of joint pathology.
METHODS
Fibroblast-like synoviocytes (FLS) were isolated from the synovial membrane of patients with RA. The FLS cultures were stimulated with polyclonal ACPAs (anti-CCP-2 antibodies) purified from the peripheral blood of patients with RA or with monoclonal ACPAs derived from single synovial fluid B cells. We analysed how ACPAs modulate FLS by measuring cell adhesion and mobility as well as cytokine production. Expression of protein arginine deiminase (PAD) enzymes and protein citrullination were analysed by immunofluorescence, and signal transduction was studied using immunoblotting.
RESULTS
Challenge of FLS by starvation-induced stress or by exposure to the chemokine interleukin-8 was essential to sensitise the cells to ACPAs. These challenges led to an increased PAD expression and protein citrullination and an ACPA-mediated induction of FLS migration through a mechanism involving phosphoinositide 3-kinase activation. Inhibition of the PAD enzymes or competition with soluble citrullinated proteins or peptides completely abolished the ACPA-induced FLS migration. Different monoclonal ACPAs triggered distinct cellular effects in either fibroblasts or osteoclasts, suggesting unique roles for individual ACPA clones in disease pathogenesis.
CONCLUSION
We propose that transient synovial insults in the presence of a certain pre-existing ACPA repertoire might result in an ACPA-mediated increase of FLS migration
Unique archaeal assemblages in the Arctic Ocean unveiled by massively parallel tag sequencing
10 páginas, 4 figuras, 1 tabla.The Arctic Ocean plays a critical role in controlling nutrient budgets between the Pacific and Atlantic Ocean. Archaea are key players in the nitrogen cycle and in cycling nutrients, but their community composition has been little studied in the Arctic Ocean. Here, we characterize archaeal assemblages from surface and deep Arctic water masses using massively parallel tag sequencing of the V6 region of the 16S rRNA gene. This approach gave a very high coverage of the natural communities, allowing a precise description of archaeal assemblages. This first taxonomic description of archaeal communities by tag sequencing reported so far shows that it is possible to assign an identity below phylum level to most (95%) of the archaeal V6 tags, and shows that tag sequencing is a powerful tool for resolving the diversity and distribution of specific microbes in the environment. Marine group I Crenarchaeota was overall the most abundant group in the Arctic Ocean and comprised between 27% and 63% of all tags. Group III Euryarchaeota were more abundant in deep-water masses and represented the largest archaeal group in the deep Atlantic layer of the central Arctic Ocean. Coastal surface waters, in turn, harbored more group II Euryarchaeota. Moreover, group II sequences that dominated surface waters were different from the group II sequences detected in deep waters, suggesting functional differences in closely related groups. Our results unveiled for the first time an archaeal community dominated by group III Euryarchaeota and show biogeographical traits for marine Arctic Archaea.P E Galand is supported by a Marie Curie grant (CRENARC MEIF-CT-2007–040247). EO Casamayor was supported by a Spanish grant CGL2006–12058-BOS, and D L Kirchman by NSF OPP ARC-0632233. C Lovejoy would like to acknowledge the support of the Natural Sciences and Engineering Council, Canada (NSERC) Special Research Opportunity Fund. We thank C Pedros-Alio for support during CASES. Deep Arctic samples were collected by K Scarcella and E Didierjean, and we thank the Chief Scientist, Officers and Crew of the CCGS Louis St Laurent and support from Fisheries and Oceans Canada. Tag sequencing was supported by a Keck foundation grant to M Sogin and L Ameral Zettler. This is a contribution to the International Census of Marine Microbes (ICOMM).Peer reviewe
Hydrography shapes bacterial biogeography of the Deep Arctic Ocean
13 páginas, 5 figuras, 2 tablas.It has been long debated as to whether marine microorganisms have a ubiquitous distribution or patterns of biogeography, but recently a consensus for the existence of microbial biogeography is emerging. However, the factors controlling the distribution of marine bacteria remain poorly understood. In this study, we combine pyrosequencing and traditional Sanger sequencing of the 16S rRNA gene to describe in detail bacterial communities from the deep Arctic Ocean. We targeted three separate water masses, from three oceanic basins and show that bacteria in the Arctic Ocean have a biogeography. The biogeographical distribution of bacteria was explained by the hydrography of the Arctic Ocean and subsequent circulation of its water masses. Overall, this first taxonomic description of deep Arctic bacteria communities revealed an abundant presence of SAR11 (Alphaproteobacteria), SAR406, SAR202 (Chloroflexi) and SAR324 (Deltaproteobacteria) clusters. Within each cluster, the abundance of specific phylotypes significantly varied among water masses. Water masses probably act as physical barriers limiting the dispersal and controlling the diversity of bacteria in the ocean. Consequently, marine microbial biogeography involves more than geographical distances, as it is also dynamically associated with oceanic processes. Our ocean scale study suggests that it is essential to consider the coupling between microbial and physical oceanography to fully understand the diversity and function of marine microbes.Financial and ship time support from Fisheries and
Oceans Canada and the Canadian International Polar
Year Program’s Canada’s Three Oceans project and the
Nansen and Amundsen Basins Observational System
project. PE Galand was supported by a Marie Curie
Grant (CRENARC MEIF-CT-2007-040247) and EO
Casamayor by the Spanish Grant CGL2006-12058-BOS.
C Lovejoy would like to acknowledge the support of
the Natural Sciences and Engineering Council, Canada
(NSERC) Special Research Opportunity Fund and
ArcticNet. Deep Arctic samples were collected by
K Scarcella, E Didierjean and M-E´ Garneau. Pyrosequencing was supported by a Keck foundation grant
to M Sogin and L Ameral Zettler. This is a contribution
to the International Census of Marine Microbes (ICOMM).Peer reviewe