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A correction is presented to the article "Assessment of Digital Image Correlation Measurement Errors: Methodology and Results [Experimental Mechanics 49(3)]" which was published in previous issue of the periodical.

This paper deals with the development of an experimental method to make measurements by the digital image correlation technique during a dynamic test on a biaxial tensile system. The aim of this method is to be able to cover a complete cycle of a dynamic test, regardless of its form and to follow a position during a long time test. Results are presented for different measurement fields.

The aim of this work is to estimate errors related to Stereo-correlation technique applied to measurements of displacements. In a first step, the influence of the cameras positions is tested using a standard object. In a second step, an evaluation of the stereo-correlation system is achieved. It is based on the generation of synthetic images representative of real speckle patterns deformed. With these images, various parameters are treated in order to determine their impact on the measurement error.

Fas-associated death domain (FADD) is a key adaptor molecule involved in numerous physiological processes including cell death, proliferation, innate immunity and inflammation. Therefore, changes in FADD expression have dramatic cellular consequences. In mice and humans, FADD regulation can occur through protein secretion. However, the molecular mechanisms accounting for human FADD secretion were still unknown. Here we report that canonical, non-canonical, but not alternative, NLRP3 inflammasome activation in human monocytes/macrophages induced FADD secretion. NLRP3 inflammasome activation by the bacterial toxin nigericin led to the proinflammatory interleukin-1β (IL-1β) release and to the induction of cell death by pyroptosis. However, we showed that FADD secretion could occur in absence of increased IL-1β release and pyroptosis and, reciprocally, that IL-1β release and pyroptosis could occur in absence of FADD secretion. Especially, FADD, but not IL-1β, secretion following NLRP3 inflammasome activation required extracellular glucose. Thus, FADD secretion was an active process distinct from unspecific release of proteins during pyroptosis. This FADD secretion process required K + efflux, NLRP3 sensor, ASC adaptor and CASPASE-1 molecule. Moreover, we identified FADD as a leaderless protein unconventionally secreted through microvesicle shedding, but not exosome release. Finally, we established human soluble FADD as a new marker of joint inflammation in gout and rheumatoid arthritis, two rheumatic diseases involving the NLRP3 inflammasome. Whether soluble FADD could be an actor in these diseases remains to be determined. Nevertheless, our results advance our understanding of the mechanisms contributing to the regulation of the FADD protein expression in human cells.

Recently clusterin (CLU) was reported to be an inhibitor of NF-κB pathway and involved in rheumatoid arthritis (RA) synovitis. This study was designed to decipher the molecular network linked to CLU expression in FLS (fibroblast-like synoviocytes) and evaluate the consequences of its low expression in conditions of TNF-α stimulation. FLS were transfected with siRNA for CLU or not and cultured for 24 and 48 h with TNF-α or not. Pan-genomic gene expression was assayed by DNA microarray. The gene network around CLU and gene interactions were analyzed with the Ingenuity Pathway Analysis software. Downregulation of CLU resulted in modification of the expression of genes known to be directly linked to CLU and for almost 5% of the tested genes (857 out of 17,225); the upregulation of a small group of gene (e.g., TIAM1) emphasizes the hypothetical role of CLU in the pseudotumoral characteristic of FLS. The comparison of gene expression with or without TNF stimulation allowed the classification of sampled with good concordance. Moreover, differential comparison showed that CLU downregulation in RA led to a profound modification of the TNF-α response as three sets of genes emerged: 497 genes modulated by siCLU transfection with TNF stimulation, 356 genes modified because of TNF stimulation only, and 484 genes modulated during TNF stimulation with CLU expression (e.g., IL-8 and Wnt signaling genes). Using a global two-way ANOVA we could identify a set of genes defining a molecular signature of TNF response directly influenced by CLU. These results (based on differential gene expression patterns) argue that CLU downregulation in FLS alters their aggressiveness in RA synovitis.

FADD is the key adaptor transmitting the apoptotic signal mediated by death receptors. We have previously shown that FADD protein expression could be lost in vivo in cancerous cells, in mice and humans, and be used as prognostic factor. Furthermore, loss of FADD could contribute to tumor progression and aggressiveness. However, the mechanism accounting for the loss of FADD was unknown. Using in vitro-cultured mouse organ models, we demonstrated that loss of FADD occurred through a new regulatory pathway of FADD expression by secretion. The secretion of FADD is an active release following shedding of microvesicles derived from the plasma membrane. In our experimental settings, this phenomenon was restricted to 6 of 12 FADD-expressing organs. This process is calcium- and adenosine-dependent. Moreover, we identified the two receptors with low affinity to adenosine, namely A(2B) and A(3) adenosine receptors, as regulators of the FADD secretion process. Furthermore, we showed that modulating A(3) adenosine receptor can convert a nonsecreting organ into a FADD-secreting one. Finally, we reported that mouse FADD release occurred in vivo during tumor disease. These results demonstrate the existence of a new localization site (in microvesicles) and regulatory mechanism (by secretion) of the FADD protein, and the implication of adenosine receptors in this process. These data open a new field of investigation consisting of the possibility to regulate FADD expression via the modulation of adenosine receptors, which constitutes a therapeutic target in diseases in which FADD-mediated signaling is impaired.

The immunodominant epitope of bovine type II collagen (CII256-270) in Aq mice carries a hydroxylysine-264 linked galactose (Gal-Hyl264), the recognition of which is central to the development of collagen-induced arthritis. This study explores the molecular interactions involved in the engagement of T-cell receptors (TCRs) with such epitopes. Responses of three anti-CII T-cell hybridomas and clone A9.2 (all sharing close TCR sequences) to a panel of CII256-270 analogues incorporating Gal-Hyl264 with a modified side chain were determined. Recognition of naturally occurring CII256-270 peptides by either group of T cells depended strictly upon the presence of the carbohydrate and, more precisely, its intact HO-4 group. Modifications of primary amino group on the hydroxylysine side chain eliminated T-cell reactivity, notwithstanding the presence of the galactosyl moiety. Moderate stereochemical changes, such as altered sugar orientation and methylation at the galactose anchor position, were still permissive. Conversely, robust transformations affecting the relative positions of the key elements were detrimental to TCR recognition. To conclude, these data provide strong new experimental evidence that integrity of both galactose HO-4 and hydroxylysine side chain primary amino groups are mandatory for activation of anti-Gal-Hyl264 TCRs. They also indicate that there is a certain degree of TCR plasticity in peptide-TCR interactions.

Gene expression analysis of target organs might help provide new insights into the pathogenesis of autoimmune diseases. We used global gene expression profiling of minor salivary glands to identify patterns of gene expression in patients with primary Sjögren's syndrome (pSS), a common and prototypic systemic autoimmune disease. Gene expression analysis allowed for differentiating most patients with pSS from controls. The expression of 23 genes in the IFN pathways, including two Toll-like receptors (TLR8 and TLR9), was significantly different between patients and controls. Furthermore, the increased expression of IFN-inducible genes, BAFF and IFN-induced transmembrane protein 1, was also demonstrated in ocular epithelial cells by quantitative RT-PCR. In vitro activation showed that these genes were effectively modulated by IFNs in salivary gland epithelial cells, the target cells of autoimmunity in pSS. The activation of IFN pathways led us to investigate whether plasmacytoid dendritic cells were recruited in salivary glands. These IFN-producing cells were detected by immunohistochemistry in all patients with pSS, whereas none was observed in controls. In conclusion, our results support the pathogenic interaction between the innate and adaptive immune system in pSS. The persistence of the IFN signature might be related to a vicious circle, in which the environment interacts with genetic factors to drive the stimulation of salivary TLRs.

Downregulation of proapoptotic molecules like Fas or caspase 8, or upregulation of antiapoptotic molecules like FLICE inhibitory protein has been suggested to be a regulatory mechanism set up by tumor cells to block the death signal received via death receptors. In an in-depth study of the Fas/FasL-signaling pathway in thyroid tumor development, we have demonstrated that tumor cells specifically downregulate the multideath receptor adapter Fas-associated death domain (FADD). The regulation of FADD expression occurred only at the protein level. Furthermore, in the absence of FADD, Fas-signaling resulted in accelerated growth of thyrocytes. Since thyrocytes also acquired FasL expression during tumor development, the absence of FADD protein could lead to greater resistance to numerous death receptor-mediated apoptosis, stimulation of their own proliferation through Fas/FasL interaction, and the capacity to counter-attack the infiltrating lymphocytes.