Transglutaminase 2 (TG2) is an allosterically regulated enzyme with transamidating, deamidating and cell signaling activities. It is thought to catalyze sequence-specific deamidation of dietary gluten peptides in the small intestines of celiac disease patients. Because this modification has profound consequences for disease pathogenesis, there is considerable interest in the design of small molecule TG2 inhibitors. Although many classes of TG2 inhibitors have been reported, thus far an animal model for screening them to identify promising celiac drug candidates has remained elusive. Using intraperitoneal administration of the toll-like receptor 3 (TLR3) ligand, polyinosinic-polycytidylic acid (poly(I∶C)), we induced rapid TG2 activation in the mouse small intestine. Dose dependence was observed in the activation of TG2 as well as the associated villous atrophy, gross clinical response, and rise in serum concentration of the IL-15/IL-15R complex. TG2 activity was most pronounced in the upper small intestine. No evidence of TG2 activation was observed in the lung mucosa, nor were TLR7/8 ligands able to elicit an analogous response. Introduction of ERW1041E, a small molecule TG2 inhibitor, in this mouse model resulted in TG2 inhibition in the small intestine. TG2 inhibition had no effect on villous atrophy, suggesting that activation of this enzyme is a consequence, rather than a cause, of poly(I∶C) induced enteropathy. Consistent with this finding, administration of poly(I∶C) to TG2 knockout mice also induced villous atrophy. Our findings pave the way for pharmacological evaluation of small molecule TG2 inhibitors as drug candidates for celiac disease.

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SVeq Cmax is a promising noninvasive marker for assessment of small intestinal health. Further studies are warranted to establish its clinical utility for assessing gut status of patients with CD.

Metabolic oligosaccharide engineering has been employed to introduce fluorine-containing groups onto mammalian cell surfaces. Incubation of HeLa, Jurkat, and HL60 cells in culture with fluorinated sialic acid and mannosamine analogues resulted in cell-surface presentation of fluorinated glycans. Metabolic conversion of fluorinated precursors was detected and quantified by DMB-derivatization and HPLC ESI-MS analysis. Between 7% and 72% of total membrane-associated sialosides were fluorinated, depending on the precursor used and the cell type. Fluorination of mammalian cell surfaces provides a means for introducing a bioorthogonal surface for modulating noncovalent interactions such as those involved in cell adhesion.The ability to decorate the exterior of living cells with covalently attached chemical entities not normally found on cell surfaces provides a means for low background detection and highly specific chemical modification of the modified cells. Metabolic glycoengineering has proven to be a very successful tactic for attaching unnatural functionalities to cells. 1-3 In this approach, a synthetic monosaccharide similar in structure to a natural precursor in a biosynthesis pathway for a cell-surface glycan, but bearing an unnatural functional group, is incubated with cells. If the modified monosaccharide enters the cell and is processed by the biosynthetic enzymes similarly to the natural precursor, then the resulting cell-surface glycan bears the unnatural functional group. The sialic acid pathway has been extensively used for metabolic glycoengineering of cell surfaces because of its tolerance of precursors with unnatural N-acyl groups. Both unnaturally acylated neuraminic acids 4-6 and mannosamines 7-14 are processed by the pathway and have been used to present unnatural functional groups on the surfaces of cells, both in culture and in live rodents. 15-17 A wide range of unnatural groups have been successfully installed onto cell-surface sialoconjugates via glycoengineering, including chainextended N-acyl groups such as N-propanoyl-, 4 N-butanoyl-, 12,13 and N-pentanoyl-, 18 as well as N-acyl groups comprising fluoromethyl-, 6 trifluoromethyl-, 6,19 keto-, 20 azido-, 21 thio-, 11 succinato-, 6 and aryl 5,12 moieties at the 5-position of sialic acid, and amino-, acetamido-, succinatamido-, iodo-, thio-, methylthio-, and methylsulfonyl-in place of the 9-Corresponding authors: Tel.: +1 4089244962; fax: +1 4089244945; e-mail: E-mail: marc.dalarcao@science.sjsu.edu (M. D.); Tel.: +1 6176275651; fax: +1 6176273443; e-mail: E-mail: krishna.kumar@tufts.edu (K. K.). Supplementary informationSupplementary data and experimental procedures associated with this article can be found, in the online version, at xxxxxx.Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is p...