Hypercholesterolemia boosts joint destruction in chronic arthritis. An experimental model aggravated by foam macrophage infiltration

Objective

The aim of this study was to determine whether hypercholesterolemia increases articular damage in a rabbit model of chronic arthritis.

Methods

Hypercholesterolemia was induced in 18 rabbits by administrating a high-fat diet (HFD). Fifteen rabbits were fed normal chow as controls. Chronic antigen-induced arthritis (AIA) was induced in half of the HFD and control rabbits, previously immunized, by intra-articular injections of ovalbumin. After sacrifice, lipid and systemic inflammation markers were analyzed in blood serum. Synovium was analyzed by Krenn score, multinucleated cell counting, immunohistochemistry of RAM11 and CD31, and TNF-α and macrophage chemoattractant protein-1 (MCP-1) gene expression. Active bone resorption was assessed by protein expression of receptor activator of nuclear factor kappa-B ligand (RANKL), osteoprotegerin (OPG) and quantification of cathepsin K, contact surface and the invasive area of pannus into bone.

Results

Rabbits receiving the HFD showed higher total serum cholesterol, HDL, triglycerides and CRP levels than rabbits fed a normal diet. Synovitis score was increased in HFD, and particularly in AIA and AIA + HFD groups. AIA + HFD synovium was characterized by a massive infiltration of RAM11+ cells, higher presence of multinucleated foam cells and bigger vascularization than AIA. Cathepsin K+ osteoclasts and the contact surface of bone resorbing pannus were also increased in rabbits with AIA + HFD compared with AIA alone. Synovial TNF-α and MCP-1 gene expression was increased in AIA and HFD rabbits compared with healthy animals. RANKL protein expression in AIA and AIA + HFD groups was higher compared with either HFD or normal groups.

Conclusions

This experimental model demonstrates that hypercholesterolemia increments joint tissue damage in chronic arthritis, with foam macrophages being key players in this process.     

Molecular characterization and phylogenetic relationships of a protein with potential oxygen-binding capabilities in the grasshopper embryo. A hemocyanin in insects?

Arthropodan hemocyanins, prophenoloxidases (PPOs), and insect hexamerins form a superfamily of hemolymph proteins that we propose to call the AHPH superfamily. The evolutionary and functional relationships of these proteins are illuminated by a new embryonic hemolymph protein (EHP) that is expressed during early stages of development in the grasshopper embryo. EHP is a 78-kDa soluble protein present initially in the yolk sac content, and later in the embryonic hemolymph. Protein purification and peptide sequencing were used to identify an embryonic cDNA clone coding for EHP. In situ hybridization identifies hemocytes as EHP-expressing cells. As deduced from the cDNA clone, EHP is a secreted protein with two potential glycosylation sites. Sequence analysis defines EHP as a member of the AHPH superfamily. Phylogenetic analyses with all the currently available AHPH proteins, including EHP, were performed to ascertain the evolutionary history of this protein superfamily. We used both the entire protein sequence and each of the three domains present in the AHPH proteins. The phylogenies inferred for each of the domains suggest a mosaic evolution of these protein modules. Phylogenetic and multivariate analyses consistently group EHP with crustacean hemocyanins and, less closely, with insect hexamerins, relative to cheliceratan hemocyanins and PPOs. The grasshopper protein rigorously preserves the residues involved in oxygen binding, oligomerization, and allosteric regulation of the oxygen transport proteins. Although insects were thought not to have hemocyanins, we propose that EHP functions as an oxygen transport or storage protein during embryonic development.      

Towards best practices in research: Role of academic core facilities

Academic Core Facilities are optimally situated to improve the quality of preclinical research by implementing quality control measures and offering these to their users. Subject Categories: Methods & Resources, Science Policy & Publishing

During the past decade, the scientific community and outside observers have noted a concerning lack of rigor and transparency in preclinical research that led to talk of a “reproducibility crisis” in the life sciences (Baker, ²⁰¹⁶; Bespalov & Steckler, ²⁰¹⁸; Heddleston et al, ²⁰²¹). Various measures have been proposed to address the problem: from better training of scientists to more oversight to expanded publishing practices such as preregistration of studies. The recently published EQIPD (Enhancing Quality in Preclinical Data) System is, to date, the largest initiative that aims to establish a systematic approach for increasing the robustness and reliability of biomedical research (Bespalov et al, ²⁰²¹). However, promoting a cultural change in research practices warrants a broad adoption of the Quality System and its underlying philosophy. It is here that academic Core Facilities (CF), research service providers at universities and research institutions, can make a difference.It is fair to assume that a significant fraction of published data originated from experiments that were designed, run, or analyzed in CFs. These academic services play an important role in the research ecosystem by offering access to cutting‐edge equipment and by developing and testing novel techniques and methods that impact research in the academic and private sectors alike (Bikovski et al, ²⁰²⁰). Equipment and infrastructure are not the only value: CFs employ competent personnel with profound knowledge and practical experience of the specific field of interest: animal behavior, imaging, crystallography, genomics, and so on. Thus, CFs are optimally positioned to address concerns about the quality and robustness of preclinical research.     

N-glycosylation potential of maize: the human lactoferrin used as a model

In order to determine the N-glycosylation potential of maize, a monocotyledon expression system for the production of recombinant glycoproteins, human lactoferrin was used as a model. The human lactoferrin coding sequence was inserted into the pUC18 plasmid under control of the wheat glutenin promoter. Maize was stably transformed and recombinant lactoferrin was purified from the fourth generation seeds. Glycosylation was analysed by gas chromatography, lectin detection, glycosidase digestions and mass spectrometry. The results indicated that both N-glycosylation sites of recombinant lactoferrin are mainly substituted by typical plant paucimannose-type glycans, with 1,2-xylose and 1,3-linked fucose at the proximal N-acetylglucosamine, and that complex-type glycans with Lewis^a determinants are not present in maize recombinant lactoferrin.     

Cigarette smoking associates with body weight and muscle mass of patients with rheumatoid arthritis: a cross-sectional,observational study

Introduction  

Rheumatoid arthritis (RA) is associated with altered metabolism leading to muscle wasting. In the general population, cigarette smoking is known to affect body composition by reducing fat and inhibiting muscle synthesis. Even though smoking has been implicated in the pathophysiology and progression of RA, its possible effects on body composition of such patients have not been studied. This cross-sectional study aimed to identify potential associations of smoking with body weight and composition of RA patients.     

Responsibility and the sense of agency enhance empathy for pain

Being held responsible for our actions strongly determines our moral judgements and decisions. This study examined whether responsibility also influences our affective reaction to others'' emotions. We conducted two experiments in order to assess the effect of responsibility and of a sense of agency (the conscious feeling of controlling an action) on the empathic response to pain. In both experiments, participants were presented with video clips showing an actor''s facial expression of pain of varying intensity. The empathic response was assessed with behavioural (pain intensity estimation from facial expressions and unpleasantness for the observer ratings) and electrophysiological measures (facial electromyography). Experiment 1 showed enhanced empathic response (increased unpleasantness for the observer and facial electromyography responses) as participants'' degree of responsibility for the actor''s pain increased. This effect was mainly accounted for by the decisional component of responsibility (compared with the execution component). In addition, experiment 2 found that participants'' unpleasantness rating also increased when they had a sense of agency over the pain, while controlling for decision and execution processes. The findings suggest that increased empathy induced by responsibility and a sense of agency may play a role in regulating our moral conduct.     

ACSL6 is associated with the number of cigarettes smoked and its expression is altered by chronic nicotine exposure

Individuals with schizophrenia tend to be heavy smokers and are at high risk for tobacco dependence. However, the nature of the comorbidity is not entirely clear. We previously reported evidence for association of schizophrenia with SNPs and SNP haplotypes in a region of chromosome 5q containing the SPEC2, PDZ-GEF2 and ACSL6 genes. In this current study, analysis of the control subjects of the Molecular Genetics of Schizophrenia (MGS) sample showed similar pattern of association with number of cigarettes smoked per day (numCIG) for the same region. To further test if this locus is associated with tobacco smoking as measured by numCIG and FTND, we conducted replication and meta-analysis in 12 independent samples (n>16,000) for two markers in ACSL6 reported in our previous schizophrenia study. In the meta-analysis of the replication samples, we found that rs667437 and rs477084 were significantly associated with numCIG (p = 0.00038 and 0.00136 respectively) but not with FTND scores. We then used in vitro and in vivo techniques to test if nicotine exposure influences the expression of ACSL6 in brain. Primary cortical culture studies showed that chronic (5-day) exposure to nicotine stimulated ACSL6 mRNA expression. Fourteen days of nicotine administration via osmotic mini pump also increased ACSL6 protein levels in the prefrontal cortex and hippocampus of mice. These increases were suppressed by injection of the nicotinic receptor antagonist mecamylamine, suggesting that elevated expression of ACSL6 requires nicotinic receptor activation. These findings suggest that variations in the ACSL6 gene may contribute to the quantity of cigarettes smoked. The independent associations of this locus with schizophrenia and with numCIG in non-schizophrenic subjects suggest that this locus may be a common liability to both conditions.