Tissue derived fibroblast-like synoviocytes (td-FLS) are key actors in pannus formation and contribute to joint destruction and inflammation during rheumatoid arthritis (RA). Several members of the Wnt family, including Wnt5a, may contribute to RA td-FLS activation and can potentially serve as therapeutic targets.
Abstract Chondrocyte hypertrophic differentiation, a key process in endochondral ossification (EO), is also a feature of osteoarthritis leading to articular cartilage destruction. ShcA (Src homology and Collagen A) is an adaptor protein that binds to the cytoplasmic tail of receptor tyrosine kinases. We found that deletion of ShcA in chondrocytes of mice inhibits hypertrophic differentiation, alters the EO process, and leads to dwarfism. ShcA promotes ERK1/2 activation, nuclear translocation of the master transcription factor for chondrocyte hypertrophy, RunX2, while maintaining the Runx2 inhibitor YAP1 in its cytosolic inactive form. This leads to hypertrophic commitment and expression of markers of hypertrophy, such as Collagen X. In addition, ShcA deletion in chondrocytes protects from age-related osteoarthritis development in mice. Our results reveal that ShcA integrates multiple stimuli which affect the intracellular signaling processes leading to the hypertrophic commitment of chondrocytes and osteoarthritis.
Rheumatoid arthritis (RA) is a systemic autoimmune disease during which fibroblast-like synoviocytes (FLS) contribute to both joint inflammation and destruction. FLS represent the core component of the synovial membrane. Following inflammation of this membrane, an effusion of cell-rich synovial fluid (SF) fills the joint cavity. Unlikely, SF has been shown to contain fibroblasts with some shared phenotypic traits with the synovial membrane FLS. These cells are called SF-FLS and their origin is still unclear. They are either brought into the synovium via migration through blood vessels, or they could originate within the synovium and exist in projections of the synovial membrane. SF-FLS function and phenotype are poorly documented compared to recently well-characterized synovial membrane FLS subsets. Furthermore, no study has yet reported a SF-FLS single-cell profiling analysis. This review will discuss the origin and cellular characteristics of SF-FLS in patients with RA. In addition, recent advances on the involvement of SF-FLS in the pathogenesis of RA will be summarized. Current knowledge on possible relationships between SF-FLS and other types of fibroblasts, including synovial membrane FLS, circulating fibrocytes, and pre- inflammatory mesenchymal (PRIME) cells will also be addressed. Finally, recent therapeutic strategies employed to specifically target SF-FLS in RA will be discussed.
Chondrocyte hypertrophic differentiation, a key process in endochondral ossification, is also a feature of osteoarthritis leading to cartilage destruction. Here we investigated the role of the adaptor protein Src homology and Collagen A (ShcA) in chondrocyte differentiation and osteoarthritis.Mice ablated for ShcA in osteochondroprogenitor cells were generated by crossing mice carrying the Twist2-Cre transgene with ShcAflox/flox mice. Their phenotype (n = 5 to 14 mice per group) was characterized using histology, immuno-histology and western-blot. To identify the signaling mechanisms involved, in vitro experiments were conducted on wild type and ShcA deficient chondrocytes (isolated from n = 4 to 7 littermates) and the chondroprogenitor cell line ATDC5 (n = 4 independent experiments) using western-blot, cell fractionation and confocal microscopy.Deletion of ShcA decreases the hypertrophic zone of the growth plate (median between group difference -11.37% [95% confidence interval -17.34 to -8.654]), alters the endochondral ossification process, and leads to dwarfism (3 months old male mice nose-to-anus length -1.48 cm [-1.860 to -1.190]). ShcA promotes ERK1/2 activation, nuclear translocation of RunX2, the master transcription factor for chondrocyte hypertrophy, while maintaining the Runx2 inhibitor, YAP1, in its cytosolic inactive form. This leads to hypertrophic commitment and expression of markers of hypertrophy, such as Collagen X. In addition, loss of ShcA protects from age-related osteoarthritis development in mice (2 years old mice OARSI score -6.67 [-14.25 to -4.000]).This study reveals ShcA as a new player in the control of chondrocyte hypertrophic differentiation and its deletion slows down osteoarthritis development.
Transplant patients, including solid-organ transplant (SOT) and hematopoietic stem cell transplant (HSCT) recipients, are exposed to various types of complications, particularly rejection. To prevent these outcomes, transplant recipients commonly receive long-term immunosuppressive regimens that in turn make them more susceptible to a wide array of infectious diseases, notably those caused by opportunistic pathogens. Among these, invasive fungal infections (IFIs) remain a major cause of mortality and morbidity in both SOT and HSCT recipients. Despite the continuing improvement in early diagnostics and treatments of IFIs, the management of these infections in transplant patients is still complicated. Here, we provide an overview concerning the most recent trends in the epidemiology of IFIs in SOT and HSCT recipients by describing the prominent yeasts and molds species involved, the timing of post-transplant IFIs and the risk factors associated with their occurrence in these particularly weak populations. We also give special emphasis into basic research advances in the field that recently suggested a role of the global and long-term prophylactic regimen in orchestrating various biological disturbances in the organism and conditioning the emergence of the most adapted fungal strains to the particular physiological profiles of transplant patients.
Purpose: Fibroblast-like synoviocytes (FLS) represent one of the principal effectors of joint damage in rheumatoid arthritis (RA). Recent discovery of the circulating fibrocyte, a potential precursor of FLS, has raised issues regarding the characterization of fibrocytes with respect to their morphology and their biological role. In this study, we evaluated the morphology of fibrocytes in vitro and their ability to produce different extracellular matrix (ECM) components in comparison with two populations of RA FLS: synovial fluid FLS (fd-FLS) and intimal lining FLS (td-FLS). We also studied the expression of ECM regulators and a set of cytokine receptors involved in the pathogenesis of RA. Materials and Methods: Fibrocytes were cultured from peripheral blood of patients with RA. FLS were cultured from synovial fluids and tissues. ECM proteins (collagen I (col I) and fibronectin), Matrix metalloproteinases (MMP) (MMP3, and MMP9), ECM regulators (β catenin, TCF4, and c-fos), and cytokine receptors (CXCR1, CXCR2, CXCR3, IL1RI, IL1RII, and IL6Rα) were analyzed using qRT-PCR and/or western blot. Results: Our results demonstrated that fibronectin and MMP3 levels were higher in FLS compared to fibrocytes. Although MMP9 was expressed in the three cell types, its level was greater in fibrocytes than in td/fd FLS. The three cell types expressed CXCR3, IL1RI, IL1RII, and IL6Rα, while the expression of CXCR1 and CXCR2 was restricted to fibrocytes. Conclusion: Our results demonstrated that fibrocytes express ECM molecules and cytokines receptors. The observed differences between fibrocytes and FLS may be due to their distinct functions or differentiation state during RA.Abbreviations: RA: Rheumatoid ArthritisFLS: fibroblast-like synoviocytestd: tissue derivedfd: fluid derivedSF: Synovial FluidWnt: WinglessMMP: Matrix MetalloproteinaseCIA: murine collagen induced arthritisECM: Extracellular matrixcol I: Collagen ITCF/LEF: T-cell factor/lymphoid enhancer-binding factorAP1: Activator Protein 1.
Background. The detection of antiphospholipid antibodies (aPL) is of interest because of their importance in the pathogenesis of arterial or venous thrombosis. They could be a “second hit” of an inflammatory event such as infection. The aim of our study was to assess the performance of antiphospholipid antibody biomarker to predict in-hospital mortality in intensive care unit (ICU) septic patients. Methods. We conducted a prospective single-center observational study including consecutive critically ill septic adults admitted to the intensive care unit. Clinical and laboratory data including enzyme-linked immunosorbent assay for antiphospholipid antibodies (anticardiolipin (aCL), antiphosphatidylserine (aPS)) were obtained. Blood samples were collected on days 1, 3, 5, 8, and 10 of hospitalization. The primary study endpoint was ICU mortality defined as death before ICU discharge. Secondary end points included correlation between SOFA score and biological parameters. Results. A total of 53 patients were enrolled. 18.8% of patients were aPL positive. In-hospital mortality rate was 60%. Multivariate analysis showed that age and aCL at days 3 and 5 along with SOFA at day 3 were independent outcome predictors. A significant positive correlation existed between SOFA at days 3, 5, and 8 and antiphospholipid antibody concentrations. Conclusions. Our data showed that antiphospholipid was useful biomarkers for the prediction of mortality in critically ill septic patients. We found a positive correlation between SOFA score and antiphospholipid antibodies.
Fibroblast-like synoviocytes (FLS) from rheumatoid arthritis (RA) display pathogenic behavior. Various members of the Wnt pathway, especially the canonical Wnt/β-catenin cascade, may contribute to autonomous RA FLS activation. It has been shown that the two Wnt inhibitors: sFRP3 and DKK1 contribute to several critical aspects of joint biology. However, their effects on RA FLS are poorly characterized. The aim of our study was to investigate the effects of sFRP3 and DKK1 on FLS markers, Wnt components, and target oncogenes expression by RA FLS and compare the findings to osteoarthritic (OA) FLS.RA and OA FLS were treated with sFRP3 and DKK1 for 6 days. Wnt signaling components (Wnt5a, LRP5 and β-catenin), Wnt target oncogenes (cyclin E1 and WISP1), and FLS markers (fibronectin and MMP3) were analyzed using western blotting and/or qRT-PCR.Our data indicated that sFRP3 down-regulated the key gene β-catenin in RA FLS. sFRP3 decreased fibronectin, a well-known downstream effectors gene of Wnt/β-catenin pathway, and LRP5 expression in both RA and OA FLS. In OA FLS, sFRP3 induced increased expression of Wnt5a and MMP3 but did not affect their levels in RA FLS. On the other hand, DKK1 increased fibronectin expression in RA FLS and decreased its expression in OA FLS.Our results confirm the involvement of Wnt signaling in FLS transformation and show that two inhibitors of the same cascade can regulate differently the same elements and that a single inhibitor can initiate signaling depending on cellular context.FLS: fibroblast-like synoviocytes; RA: rheumatoid arthritis; Wnt: Wingless; Fz: frizzled; LRP: Fz/low-density lipoprotein receptor protein; WISP1: Wnt1 inducible signaling pathway protein 1; sFRP: secreted Fz-related proteins; DKK: Dickkopf; OA: osteoarthritis; DMEM: Dulbecco's modified Eagle's medium; FBS: fetal bovine serum; PBS: phosphate buffered saline; SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel electrophoresis; ECL: enhanced chemiluminescence detection solution; MMP3: metaloproteinase 3; qRT-PCR: quantitative real-time polymerase chain reaction; S.D: standard deviation; CRD: cysteine-rich domain; MeCP2: methyl-CpG-binding protein; RANKL: nuclear factor-kappa B ligand.
The two most studied inhibitors of the Wnt signaling pathway in spondyloarthritis (SpA) are Dickkopf-1 (DKK-1) and Sclerostin. Their dysfunction would be responsible for bone formation phenomena. Osteoprotegerin (OPG), a potent inhibitor of osteoclasts and regulated by the Wnt pathway, has also been implicated in this osteoformation phenomenon.
Objectives
Our work aimed to determine the associations between serum levels of DKK-1, Sclerostin, OPG, and markers of inflammation in SpA.
Methods
It was a cross-sectional study including patients with SpA meeting ASAS criteria. Data collected included sociodemographic and disease characteristics, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR). Biomarker assays were performed using an ELISA technique.
Results
One hundred and nine patients were included, 68 men and 41 women. The mean age of the patients was 43 ± 12 years [19-79]. The mean age of disease onset was 30.6 ± 11 years [5-56]. The mean duration of SpA at inclusion was 12.6 ± 9.8 years [1 - 62]. Forty-nine percent of patients had a biological inflammatory syndrome (BIS). The mean ESR was 28.6 ± 21.2 mm/h [10 - 110 mm/h], and the mean CRP value was 15.2 ± 23.4 mg/L [1 - 153 mg/L]. Median serum levels, in pg/mL, of DKK-1, Sclerostin, and OPG were 146.7 [0-455.3], 32.8 [0-488], and 471 [0-1613.6], respectively. The biological inflammatory syndrome was not associated with DKK1 level (p=0.800). It tended to be associated with OPG and Sclerostin levels (p=0.085 and p= 0.051, respectively). ESR was negatively correlated with Sclerostin (r=-0.222; p=0.022). The CRP level appeared to be negatively correlated with OPG (r=-0.161; p=0.099) and Sclerostin levels (r=-0.181; p=0.064).
Conclusion
An association between markers of inflammation and inhibitors of the wnt signaling pathway as well as OPG was shown by our study, suggesting that actors of systemic inflammation may influence the secretion of these biomarkers.
