Disclosed are a pharmaceutical composition and a method for preventing or treating diabetic complications caused by vascular leakage, comprising a TGase2 inhibitor, and a method of screening a preventive or therapeutic agent for diabetic complications caused by vascular leakage.

A method of detecting factor XIII activity in a biological sample is described. The method includes the steps of immobilizing or having obtained a capture antibody on a solid support, wherein the capture antibody comprises an antibody or antibody fragment that specifically binds to fibrinogen; incubating the biological sample with the capture antibody; contacting the immobilized capture antibody with -thrombin, calcium, and 2-antiplasmin (AP); contacting the immobilized capture antibody with a detection antibody or antibody fragment that specifically binds to 2-AP, wherein the detection antibody or antibody fragment includes a detection label; and determining that factor XIII activity is present if the detection label is detected. The method can be used to diagnose a subject having factor XIII deficiency, or to monitor factor XIII levels in a subject undergoing factor XIII replacement therapy.

The present invention provides a method for determining whether a subject is suffering from celiac disease by contacting a sample of bodily fluid from the subject, with an antigen formed from a gliadin fusion protein immobilized on a solid support. The gliadin fusion protein of the antigen includes a recombinant deamidated gliadin linked to a tag such as Glutathione-S transferase (GST) protein. The antigen is prepared by immobilizing on the solid support the gliadin fusion protein via the tag. The antigen can further include tissue Transglutaminase (tTG) cross-linked to the gliadin fusion protein. When tTG is present, the tTG and recombinant deamidated gliadin are mixed together prior to immobilization to the solid phase.

Fusion polypeptides are disclosed which are substrates for Kutzneria albida transglutaminase. The fusion polypeptides comprise one or more FKBP chaperone(s) and a target polypeptide. Each of these elements is separated from the neighboring element by a linker amino acid sequence. It was found that inserting glutamic acid containing transglutaminase recognition motifs into the linker amino acid chains is advantageous. Subsequent labeling reactions catalyzed by the transglutaminase surprisingly provide labeled fusion polypeptides have superior properties when compared with chemically random-labeled fusion polypeptides of similar design. Assays and kits are provided for in vitro detection of target antibodies in samples.

The present invention relates to methods for detecting crosslinks formed by transglutaminases, including NN Bis(-glutamyl)-polyamine and/or -(-glutamyl)-lysine dipeptide/isopeptide crosslinks in a sample, comprising the steps of digesting proteins present in the biological sample using enzymes immobilised on beads, and detecting said crosslinks in the biological sample by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The methods also allow for determining the activity of transglutaminases, diagnosing diseases associated with transglutaminase activity and assessing treatments.