Quantification of Tau-A in serum after brain injury: a comparison of two analytical platforms, ELISA and electrochemiluminescence immunoassay.

BACKGROUND: Previous studies have indicated the utility of the ADAM10-generated fragment of tau, Tau-A, as marker of neuronal damage. However, the sensitivity of the ELISA-based system was limited. OBJECTIVES: We utilized the extensive dynamic range of electrochemiluminescence compared to colorimetric assessment to improve the sensitivity of the Tau-A assay and investigate Tau-A levels after brain injury. METHODS: We converted the Tau-A competitive ELISA to a competitive electrochemiluminescence-based immunoassay, Tau-A ECLIA, and compared the methods by measuring serum samples in a TBI (n = 40) and a stroke cohort (n = 64). RESULTS: The Tau-A ECLIA was technically robust. Only 1% of the samples was below the detection limit in the ECLIA compared to 10.6% in the ELISA . Tau-A measured in both assays could discriminate between patients with a TBI and non-trauma controls (ELISA: p = 0.0005, ECLIA: p = 0.0002). The increased dynamic range of the Tau-A ECLIA also allowed discrimination between healthy controls from patients with hemorrhagic (p = 0.0172) and severe ischemic stroke (p = 0.0118) respectively, as well as patients with mild ischemic stroke from severe (p = 0.0445). CONCLUSIONS: The Tau-A ECLIA was characterized by dynamic range compared to the ELISA, which facilitated a better separation between the patient groups. Tau-A warrants further investigation as a neuronal injury associated marker.

Association of metabolites reflecting type III and VI collagen formation with modified Rodnan skin score in systemic sclerosis - a cross-sectional study.

Objective: The objective was to investigate blood-based biomarkers of type I (PRO-C1), III (PRO-C3) and VI (PRO-C6) collagen formation in systemic sclerosis (SSc) patients and examine their correlation to modified Rodnan skin score (mRSS). Methods: Limited (lSSc, n = 76) and diffuse SSc (dSSc, n = 41) fulfilling the ACR/EULAR 1980 and 2013 classification criteria for SSc and asymptomatic controls (n = 9) were included. PRO-C1, PRO-C3 and PRO-C6 were measured in serum. Results: LSSc compared to dSSc were significantly older, had longer disease duration and lower mRSS. PRO-C3 was higher in early dSSc compared to early lSSc (mean [95 percentile], 27.4 [13.1-39.1] ng/mL vs 14.9 [8.2-28.8] ng/mL, p = 0.006). PRO-C6 levels were higher in early dSSc compared to early lSSc and late dSSc (early dSSc: 28.2 [10.4-92.3] ng/ml vs early lSSc: 11.0 [6.9-28.5] ng/ml; p = 0.006 and late dSSc: 12.6 [6.5-25.3] ng/mL, p = 0.04). No difference was observed with PRO-C1. PRO-C3 and PRO-C6 were moderately correlated with mRSS with R-partials of 0.36 (p < 0.001) and 0.29 (p = 0.002), respectively Conclusion: Measures of type III and VI collagen formation are potential objective biomarkers of fibrosis in systemic sclerosis. These biomarkers could be useful in monitoring the disease and efficacy of treatment.

Fibrogenesis Marker PRO-C3 Is Higher in Advanced Liver Fibrosis and Improves in Patients Undergoing Bariatric Surgery.

CONTEXT: Serum propeptides of type III and type VI collagen (PRO-C3 and PRO-C6) are elevated in advanced nonalcoholic fatty liver disease (NAFLD), but their value in patients with severe obesity and their evolution after bariatric surgery (BS) is unknown. It is unclear if these markers of fibrogenesis are affected by adipose tissue fibrosis (ATF). OBJECTIVE: We studied the association of PRO-C3 and PRO-C6 with liver fibrosis before BS, examined their evolution after BS, and evaluated how much patients' ATF contribute to their levels. METHODS: Serum PRO-C3 and PRO-C6 were measured in 158 BS patients and compared with liver, subcutaneous, and omental adipose tissue histology obtained during surgery. PRO-C3 and PRO-C6 levels of 63 patients were determined in follow-up at 3 and 12 months post-BS. RESULTS: Patients in the highest quartile of PRO-C3 had a higher risk of advanced liver fibrosis (stage F3-4; odds ratio 5.8; 95% CI [1.5-29.9]; P = 0.017) vs the lowest quartile (adjustment for age, gender, and BMI). PRO-C3 was positively correlated with markers of insulin resistance and liver enzymes. After BS, PRO-C3 levels decreased in patients with high baseline liver fibrosis. This decrease correlated with improvement of metabolic and liver parameters. PRO-C6 was not related to stage of liver fibrosis. ATF did not correlate with PRO-C3 or PRO-C6 levels at baseline or after BS. CONCLUSION: PRO-C3 was associated with advanced liver fibrosis in patients with severe obesity, and decreased after BS, without being affected by ATF. These data suggest that BS prominently eliminates drivers of hepatic fibrogenesis in NAFLD.

Pressure overload induced right ventricular remodeling is not attenuated by the anti-fibrotic agent pirfenidone.

Cardiac fibrosis contributes to the development of heart failure in pulmonary hypertension. We aimed to assess the development of fibrosis and the effects of treatment with the anti-fibrotic agent pirfenidone in pressure overload induced right ventricular (RV) failure. Wistar rat weanlings were randomized to pulmonary trunk banding (PTB) or sham surgery. One week after the procedure, PTB rats were randomized into two groups with either six weeks on standard chow or treatment with pirfenidone mixed in chow (700 mg/kg/day). RV hemodynamic effects were evaluated by echocardiography, cardiac magnetic resonance imaging (MRI), and pressure-volume measurements. Sections from the isolated RV, left ventricle, and septum were sampled systematically; stereological point grids and the nucleator were used to estimate volume of fibrosis and cardiac hypertrophy, respectively. PTB caused RV failure in all rats subjected to the procedure. The volume fraction of fibrosis in the RV increased threefold in PTB rats corresponding to a sixfold increase in total volume of RV fibrosis. Volume fraction of fibrosis and total volume of fibrosis also increased in the septum and in the left ventricle. Pirfenidone reduced body weight but did not improve RV hemodynamics or reduce cardiac fibrosis. RV cardiomyocyte profile area was increased twofold in PTB rats without any effect of pirfenidone. RV pressure overload after PTB induced not only RV but also septal and left ventricular fibrosis assessed by stereology. Treatment with pirfenidone reduced body weight but did not reduce the development of cardiac fibrosis or delay the progression of RV failure.

Mechanisms of the anabolic effects of teriparatide on bone: insight from the treatment of a patient with pycnodysostosis.

Pycnodysostosis is an extremely rare genetic osteosclerosis caused by cathepsin K deficiency. We hypothesized that teriparatide, a potent anabolic agent used in the treatment of osteoporosis, might reduce skeletal fragility by activating bone turnover. We studied a typical case of pycnodysostosis in a 37-yr-old woman who exhibited short stature, skull and thorax deformities, and a history of severe fragility fractures. Cathepsin K gene sequencing was performed. Before and after 6 mo of 20 microg/d teriparatide, biochemical markers of bone turnover were measured, and 3D bone structure and microarchitecture was assessed in vivo by HR-pQCT. Qualitative and quantitative analysis of transiliac bone biopsies were performed, and the degree of mineralization was evaluated by quantitative microradiography. In vitro assessment of bone resorption was performed after separation and differentiation of CD14(+) monocytes from peripheral blood. Bone structure assessed by HR-pQCT on the radius and tibia showed augmentation of cortical and trabecular density. Transiliac bone biopsy showed highly increased bone mass (+63% versus age- and sex-matched controls), a decrease in bone remodeling without evidence of active osteoblasts, and a severe decrease in the dynamic parameters of bone formation (mineralizing surfaces, -90% and bone formation rate, -93% versus age- and sex-matched controls). This depressed bone turnover probably explained the increased degree of mineralization. The presence of a novel missense mutation leading to an A141V amino acid substitution confirmed a genetic defect of cathepsin K as the cause of the disease. The deficiency of active osteoclasts was confirmed by an in vitro study that showed a decreased concentration of CD14(+) monocytes (the precursor of osteoclasts) in blood. These osteoclasts had low resorptive activity when incubated on bone slices. After 6 mo of teriparatide, the structure, microarchitecture, and turnover of bone--assessed by HR-pQCT, histology, and bone turnover markers--remained unchanged. Our data strongly suggest that some features of the osteoclastic phenotype--that are absent in pycnodysostosis--are a prerequisite for the anabolic effect of PTH on osteoblasts.