No abstract

A SNP in the gene PTPN22 is associated with type 1 diabetes, rheumatoid arthritis, lupus, Graves thyroiditis, Addison disease and other autoimmune disorders. T cells from carriers of the predisposing allele produce less interleukin-2 upon TCR stimulation, and the encoded phosphatase has higher catalytic activity and is a more potent negative regulator of T lymphocyte activation. We conclude that the autoimmune-predisposing allele is a gain-of-function mutant.

Lymphoid tyrosine phosphatase (LYP) and C-terminal Src kinase (CSK) are negative regulators of signaling mediated through the T cell antigen receptor (TCR) and are thought to act in a cooperative manner when forming a complex. Here, we studied the spatio-temporal dynamics of the LYP/CSK complex in T cells. We demonstrate that dissociation of this complex is necessary for recruitment of LYP to the plasma membrane, where it down-modulates TCR signaling. Development of a potent and selective chemical probe of LYP confirmed that LYP inhibits T cell activation when removed from CSK. Our findings may explain the reduced TCR-mediated signaling associated with a single nucleotide polymorphism, which confers increased risk for certain autoimmune diseases, including type 1 diabetes and rheumatoid arthritis, and results in expression of a LYP allele that is unable to bind CSK. Our compound also represents a starting point for the development of a LYP-based treatment of autoimmunity.

Ticagrelor reversibly inhibits the platelet adenosine diphosphate P2Y 12 receptor (P2Y 12). 1 It is approved for prevention of cardiovascular events in patients with atherosclerotic cardiovascular disease and shows evidence of superior clinical performance compared with other P2Y 12 inhibitors. A post hoc analysis of the Comparison of Ticagrelor (AZD6140) and Clopidogrel in Patients With Acute Coronary Syndrome (PLATO) trial 2 revealed that patients treated with ticagrelor had a lower risk of infection-related death than those treated with clopidogrel bisulfate. 3 More recently, in the Targeting Platelet-Leukocyte Aggregates in Pneumonia With Ticagrelor (XANTHIPPE) study, ticagrelor was associated with improved lung function in patients hospitalized for pneumonia. 4 We therefore questioned whether ticagrelor or its metabolites could possess antimicrobial properties. Methods | Tic agrelor and its major metabolites (M5 AR-C133913, M7, M8 AR-C124910) 5 were synthetized and tested in time-kill assays against gram-positive methicillinresistant Staphylococcus epidermidis RP62A (MRSE) (ATCC 35984); methicillin-sensitive Staphylococcus aureus (MSSA) (ATCC 25904, ATCC 6538); glycopeptide intermediate S aureus (GISA) Mu-50 (ATCC 700699); methicillin-resistant S aureus (MRSA) (ATCC BAA-1556); Enterococcus faecalis (ATCC 29212); vancomycin-resistant E faecalis (VRE) (ATCC BAA-2365); and Streptococcus agalactiae (ATCC 12386) and against gram-negative Escherichia coli (ATCC 8739) and Pseudomonas aeruginosa (PAK laboratory strain). Biofilm formation was assessed in vitro with crystal violet staining and in a mouse model of S aureus polyurethane-implant infection using Xen-29 bacteria (Perkin Elmer). Infected disks were implanted in specific pathogen-free BALB/cAnCrl mice (Charles River). The mouse protocol was approved by the ethical committee of Liège University.