siRNA knockdown of SPHK1 in vivo protects mice from systemic, type-I Allergy.

Systemic anaphylaxis is considered to be a typical immediate hypersensitivity response, determined by the activation of immune cells,
via antigen-induced aggregation of IgE-sensitized FcεRI cells. Perhaps most the important cells, in the immediate hypersensitivity responses, are mast cells. We have previously shown that SPHK1 plays a key role in the intracellular signaling pathways triggered by FceRI aggregation on human
mast cells. More recently, we performed a genome-wide gene expression profiling of human mast cells, sensitized with IgE alone, or stimulated by FcεRI aggregation. We found that sphingosine kinase 1 (SPHK1) was one
of genes activated at the earlier stages of mast cell activation, including during sensitization. Moreover, SPHK1 has been shown, by us and others, to be a key player in the intracellular signaling pathways triggered by
several immune-receptors, including fMLP, C5a, and Fcg- and Fcereceptors. Here we have investigated the in vivo role of SPHK1 in allergy, using a specific siRNA to knockdown SPHK1 in vivo. Our results support a role for
SPHK1 in the inflammatory responses that share clinical, immunological, and histological features of type I hypersensitivity. Thus, mice pretreated with the siRNA for SPHK1 were protected from the IgE mediated allergic
reactions including: temperature changes, histamine release, cytokine production, cell-adhesion molecule expression, and immune cell infiltration into the lungs

Genome activity profiling of monomeric-IgE and Fc-epsilon-RI-aggregation on human mast cells reveals a complex network of genes involved in inflammatory responses.

Mast cell activation, mediates type-1 allergic responses, one of the most powerful reactions of the immune system. However, mast cells activation is becoming increasingly linked to inflammatory, autoimmunity, and to adaptive immunity by regulating T-cell activation.
Here we analyzed the gene expression pattern in IgE-sensitized and FcεRI aggregation on human mast cells. Our data revealed coordinated changes in gene expression. We observed increased expression of gene-transcripts involved in allergic, innate and adaptive
immune responses. Among the most prominent findings is the increased expression of transcripts encoding for MIP3a, SPARCL1, AREG, IL18, CCL1, TNFRSF9, IL1b, CX3CR1, PTGER3, MIF, MMP12, ADORA3, IL8RB, and other genes involved in innate and cellmediated
immunity. These results represent a substantial advance in our understanding of the genome-wide effects triggered by “passive sensitization” or active stimulation of human mast cells, and how this relate to mast cells involvement not only in allergic
responses but also in innate and adaptive immunity

The clusterin connectome:emerging players in chondrocyte biology and putative exploratory biomarkers of osteoarthritis

Abstract Introduction: Clusterin is a moonlighting protein that has many functions. It is a multifunctional holdase chaperone glycoprotein that is present intracellularly and extracellularly in almost all bodily fluids. Clusterin is involved in lipid transport, cell differentiation, regulation of apoptosis, and clearance of cellular debris, and plays a protective role in ensuring cellular survival. However, the possible involvement of clusterin in arthritic disease remains unclear. Given the significant potential of clusterin as a biomarker of osteoarthritis (OA), a more detailed analysis of its complex network in an inflammatory environment, specifically in the context of OA, is required. Based on the molecular network of clusterin, this study aimed to identify interacting partners that could be developed into biomarker panels for OA. Methods: The STRING database and Cytoscape were used to map and visualize the clusterin connectome. The Qiagen Ingenuity Pathway Analysis (IPA) software was used to analyze and study clusterin associated signaling networks in OA. We also analyzed transcription factors known to modulate clusterin expression, which may be altered in OA. Results: The top hits in the clusterin network were intracellular chaperones, aggregate-forming proteins, apoptosis regulators and complement proteins. Using a text-mining approach in Cytoscape, we identified additional interacting partners, including serum proteins, apolipoproteins, and heat shock proteins. Discussion: Based on known interactions with proteins, we predicted potential novel components of the clusterin connectome in OA, including selenoprotein R, semaphorins, and meprins, which may be important for designing new prognostic or diagnostic biomarker panels

Exploring the translational potential of clusterin as a biomarker of early osteoarthritis

Abstract Background: Clusterin (CLU; also known as apolipoprotein J) is an ATP-independent holdase chaperone that prevents proteotoxicity as a consequence of protein aggregation. It is a ∼60 kDa disulfide-linked heterodimeric protein involved in the clearance of cellular debris and the regulation of apoptosis. CLU has been proposed to protect cells from cytolysis by complement components and has been implicated in Alzheimer’s disease due to its ability to bind amyloid-β peptides and prevent aggregate formation in the brain. Recent studies suggest that CLU performs moonlighting functions. CLU exists in two major forms: an intracellular form and a secreted extracellular form. The intracellular form of CLU may suppress stress-induced apoptosis by forming complexes with misfolded proteins and facilitates their degradation. The secreted form of CLU functions as an extracellular chaperone that prevents protein aggregation. Methods: In this review, we discuss the published literature on the biology of CLU in cartilage, chondrocytes, and other synovial joint tissues. We also review clinical studies that have examined the potential for using this protein as a biomarker in synovial and systemic fluids of patients with rheumatoid arthritis (RA) or osteoarthritis (OA). Results: Since CLU functions as an extracellular chaperone, we propose that it may be involved in cytoprotective functions in osteoarticular tissues. The secreted form of CLU can be measured in synovial and systemic fluids and may have translational potential as a biomarker of early repair responses in OA. Conclusion: There is significant potential for investigating synovial and systemic CLU as biomarkers of OA. Future translational and clinical orthopaedic studies should carefully consider the diverse roles of this protein and its involvement in other comorbidities. Therefore, future biomarker studies should not correlate circulating CLU levels exclusively to the process of OA pathogenesis and progression. Special attention should be paid to CLU levels in synovial fluid. The Translational potential of this article: There is significant potential for investigating synovial and systemic CLU as a predictive biomarker of osteoarthritis (OA) progression and response to novel treatments and interventions. Given that CLU plays diverse roles in other comorbidities such as rheumatoid arthritis (RA) and obesity, future translational and clinical orthopaedic biomarker studies should not directly correlate circulating CLU levels to the process of OA pathogenesis and progression. However, special attention should be paid to CLU levels in synovial fluid. The cytoprotective properties of CLU may support the implementation of regenerative strategies and new approaches for developing targeted therapeutics for OA