The applicability of ELISA detection of gastric mucosa-expressing proteins for the identification of vomit

Proteomics for forensic identification of saliva and vomit in a case of alleged rape

In crime investigations, the unambiguous identification of biological traces can be decisive for framing the events. In this study, we applied proteomics to analyze scant amounts of biological residues in the context of an alleged rape case, focusing on the detection of traces of vomit. We used high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and two distinct proteomic workflows to identify proteins and possible proteolytic peptides in biological residues from clothing, bedding, and car upholstery from the alleged crime scene. Specifically, a fragment of pillowcase contained a protein pattern indicative of human saliva and a complex panel of peptides resulting from extensive hydrolysis of salivary proteins. The presence of partly digested proteins from bovine meat, wheat, and eggs, along with salivary and gastric enzymes, demonstrated the presence of vomit on the alleged victim's trousers, also providing insights into the recently consumed meal. A drop of cow's milk on the seat of the suspect's car was likely irrelevant to the criminal act. Other fabric samples showed only common contaminants, excluding significant biological traces or food-derived proteins. These findings support the judicial decision regarding consent to sexual intercourse, for which DNA individualization lacks evidentiary power, and establish a reference for annotating saliva and vomit traces in forensic investigations.

Urinary fetuin-A peptides as a new marker for impaired kidney function in patients with type 2 diabetes

Background

The hepatokine fetuin-A, released by the human liver, promotes pro-inflammatory effects of perivascular fat. The involvement of inflammation in type 2 diabetes mellitus (T2DM) can affect the kidney and contribute to the development of diabetic kidney disease. Therefore we examined the association of urinary fetuin-A protein fragments with renal damage in T2DM patients.

Methods

Urinary peptides of 1491 individuals using proteome data available from the human urine proteome database were analysed. Prediction of proteases involved in urinary peptide generation was performed using the Proteasix tool.

Results

We identified 14 different urinary protein fragments that belong to the region of the connecting peptide (amino acid 301–339) of the total fetuin-A protein. Calpains (CAPN1 and CAPN2), matrix metalloproteinase and pepsin A-3 were identified as potential proteases that were partially confirmed by previous in vitro studies. Combined fetuin-A peptides (mean of amplitudes) were significantly increased in T2DM patients with kidney disease and to a lesser extent with cardiovascular risk. Furthermore, fetuin-A peptide levels displayed a significant negative correlation with baseline estimated glomerular filtration rate (eGFR) values (r = −0.316, P < 0.0001) and with the slope (%) of eGFR per year (r = −0.096, P = 0.023). A multiple regression model including fetuin-A peptide and albuminuria resulted in a significantly improved correlation with eGFR (r = −0.354, P < 0.0001) compared with albuminuria, indicating an added value of this novel biomarker.

Conclusions

The urinary proteome analysis demonstrated the association of fetuin-A peptides with impaired kidney function in T2DM patients. Furthermore, fetuin-A peptides displayed early signs of kidney damage before albuminuria appeared and therefore can be used as markers for kidney disease detection.