Rheumatoid synovial fluid interleukin-17-producing CD4 T cells have abundant tumor necrosis factor-alpha co-expression,but little interleukin-22 and interleukin-23R expression

Introduction  

Th17 cells have been implicated in the pathogenesis of rheumatoid arthritis (RA). The aim of this study was to systematically analyse the phenotype, cytokine profile and frequency of interleukin-17 (IL-17) producing CD4-positive T cells in mononuclear cells isolated from peripheral blood, synovial fluid and synovial tissue of RA patients with established disease, and to correlate cell frequencies with disease activity.     

Cellular factors implicated in prion replication

Prions are the unconventional infectious agents responsible for prion diseases, which are composed mainly by the misfolded prion protein (PrP^Sc) that replicates by converting the host associated cellular prion protein (PrP^C). Several lines of evidence suggest that other cellular components participate in prion conversion, however, the identity or even the chemical nature of such factors are entirely unknown. In this article we study the conversion factor activity by complementation of a PMCA procedure employing purified PrP^C and PrP^Sc. Our results show that the conversion factor is present in all major organs of diverse mammalian species, and is predominantly located in the lipid raft fraction of the cytoplasmic membrane. On the other hand, it is not present in the lower organisms tested (yeast, bacteria and flies). Surprisingly, treatments that eliminate the major classes of chemical molecules do not affect conversion activity, suggesting that various different compounds may act as conversion factor in vitro. This conclusion is further supported by experiments showing that addition of various classes of molecules have a small, but detectable effect on enhancing prion replication in vitro. More research is needed to elucidate the identity of these factors, their detailed mechanism of action and whether or not they are essential component of the infectious particle.     

Are there ventricle-specific postnatal maturational differences in myocardial beta-adrenoceptors?

Newborn hearts have restricted functional reserve and variable responsiveness to inotropes that could be partly due to differences in myocardial beta-adrenoceptors (beta-AR). To clarify this issue, this study documented ventricle-specific changes in myocardial beta-AR density and affinity during postnatal maturation. In vivo left and right ventricle (LV and RV, respectively) biopsies were obtained from newborn (3-day-old, n = 11), immature (14-day-old, n = 7), and adult (n = 6) pigs. Total beta-AR density (B(max), fmol/g) and dissociation constant (K(d), pmol/L) were determined by radioligand binding with I125 iodocyanopindolol. Overall, beta-AR B(max) in the LV significantly decreased with maturation. Interestingly, newborn animal hearts (LV and RV) subdivided into 2 groups: an adult-like low K(d) group with low B(max) and a fetal-like high K(d) group with high B(max), which were significantly different from one another. The high K(d) newborn group also had significantly higher K(d) and B(max) than both immature and adult hearts. Newborns had similar Bmax but higher Kd in the LV than the RV, whereas immature and adult hearts did not have ventricular differences. During maturation, beta-AR density decreased, whereas LV beta-AR binding affinity increased. Variable beta-AR maturity was also identified immediately post partum, which could potentially explain the newborn heart's variable responsiveness to inotropes. The subset of newborn hearts with lower binding affinity (reduced responsiveness) could also contribute to the newborn heart's overall reduction in functional reserve.     

NQO1 and NQO2 regulation of humoral immunity and autoimmunity

NAD(P)H:quinone oxidoreductase 1 (NQO1) and NRH:quinone oxidoreductase 2 (NQO2) are cytosolic enzymes that catalyze metabolic reduction of quinones and derivatives. NQO1-null and NQO2-null mice were generated that showed decreased lymphocytes in peripheral blood, myeloid hyperplasia, and increased sensitivity to skin carcinogenesis. In this report, we investigated the in vivo role of NQO1 and NQO2 in immune response and autoimmunity. Both NQO1-null and NQO2-null mice showed decreased B-cells in blood, lower germinal center response, altered B cell homing, and impaired primary and secondary immune responses. NQO1-null and NQO2-null mice also showed susceptibility to autoimmune disease as revealed by decreased apoptosis in thymocytes and pre-disposition to collagen-induced arthritis. Further experiments showed accumulation of NADH and NRH, cofactors for NQO1 and NQO2, indicating altered intracellular redox status. The studies also demonstrated decreased expression and lack of activation of immune-related factor NF-kappaB. Microarray analysis showed altered chemokines and chemokine receptors. These results suggest that the loss of NQO1 and NQO2 leads to altered intracellular redox status, decreased expression and activation of NF-kappaB, and altered chemokines. The results led to the conclusion that NQO1 and NQO2 are endogenous factors in the regulation of immune response and autoimmunity.     

CRIg: a macrophage complement receptor required for phagocytosis of circulating pathogens

The complement system serves an important role in clearance of pathogens, immune complexes, and apoptotic cells present in the circulation. Complement fragments deposited on the particle surface serve as targets for complement receptors present on phagocytic cells. Although Kupffer cells, the liver resident macrophages, play a dominant role in clearing particles in circulation, complement receptors involved in this process have yet to be identified. Here we report the identification and characterization of a Complement Receptor of the Immunoglobulin superfamily, CRIg, that binds complement fragments C3b and iC3b. CRIg expression on Kupffer cells is required for efficient binding and phagocytosis of complement C3-opsonized particles. In turn, Kupffer cells from CRIg-deficient mice are unable to efficiently clear C3-opsonized pathogens in the circulation, resulting in increased infection and mortality of the host. CRIg therefore represents a dominant component of the phagocytic system responsible for rapid clearance of C3-opsonized particles from the circulation.     

A longitudinal study of infant faecal microbiota during weaning

For infants, the introduction of food other than breast milk is a high risk period due to diarrheal diseases, and may be corroborated with a shift in the faecal microbiota. This longitudinal study was the first undertaken to understand the effect of the supplementation on the infant's faecal microbiota and particularly the bifidobacteria. Eleven infants were enrolled. Their faecal microbiota were analysed using temporal temperature gradient gel electrophoresis (TTGE) with bacterial and bifidobacterial primers. In parallel, bifidobacterial counts were followed using competitive PCR. Three periods were distinguished: exclusive breastfeeding (Bf period), weaning (i.e. formula-milk addition, W period) and postweaning (i.e. breastfeeding cessation, Pw period). The bifidobacterial counts were not modified, reaching 10.5 (Log10 cells g(-1) wet weight). In the TTGE profiles, the main identified bands corresponded to Escherichia coli, Ruminococcus sp. and Bifidobacterium sp., more precisely Bifidobacterium longum, Bifidobacterium infantis and Bifidobacterium breve. For both TTGE profiles, the analysis of the distance suggested a maturation of the faecal microbiota but no correlation could be established with the diet. Despite a high interindividual variability, composition of the faecal microbiota appeared more homogenous after weaning and this point may be correlated with the cessation of breastfeeding.     

Replication and long-term persistence of bovine and human strains of Mycobacterium avium subsp. paratuberculosis within Acanthamoeba polyphaga

Free-living protists are ubiquitous in the environment and form a potential reservoir for the persistence of animal and human pathogens. Mycobacterium avium subsp. paratuberculosis is the cause of Johne's disease, a systemic infection accompanied by chronic inflammation of the intestine that affects many animals, including primates. Most humans with Crohn's disease are infected with this chronic enteric pathogen. Subclinical infection with M. avium subsp. paratuberculosis is widespread in domestic livestock. Infected animals excrete large numbers of robust organisms into the environment, but little is known about their ability to replicate and persist in protists. In the present study we fed laboratory cultures of Acanthamoeba polyphaga with bovine and human strains of M. avium subsp. paratuberculosis. Real-time PCR showed that the numbers of the pathogens fell over the first 4 to 8 days and recovered by 12 to 16 days. Encystment of the amoebic cultures after 4 weeks resulted in a 2-log reduction in the level of M. avium subsp. paratuberculosis, which returned to the original level by 24 weeks. Extracts of resection samples of human gut from 39 patients undergoing abdominal surgery were fed to cultures of A. polyphaga. M. avium subsp. paratuberculosis detected by nested IS900 PCR with amplicon sequencing and visualized by IS900 in situ hybridization and auramine-rhodamine staining was found in cultures derived from 13 of the patients and was still present in the cultures after almost 4 years of incubation. Control cultures were negative. M. avium subsp. paratuberculosis has the potential for long-term persistence in environmental protists.     

The cellulose/lignin assembly assessed by molecular modeling. Part 2: Seeking for evidence of organization of lignin molecules at the interface with cellulose.

We have extended our previous computational investigation of the cellulose lignin assembly by considering more complex systems. Surface coverage of cellulose, structural parameters such as molecular mass and structural features of the lignin models and the presence of an explicit hydrated environment have been taken into account to examine their influence on the associative interactions between cellulose and lignin. To this end, different lignin molecular models, from beta-O-4 dimers up to a 20-units oligomer, were considered. Independently of the system studied, the key feature of the adsorption is globally preserved: aromatic rings of lignin adopt a preferential parallel orientation relative to the cellulose surface. Such structural order appears to be limited to the first shell of lignin units adsorbed on the cellulose. The pre-organization of the lignin monolayer at the surface of cellulose is not significantly changed at the interface with water. However, adsorption significantly depends on the molecular mass and the structure of lignin. The structural order is significantly hindered by the presence of branching or some particular inter-units linkages in the structure of lignin. Such results rationalize the apparent contradiction between the available experimental results.