CD83 expression is essential for Treg cell differentiation and stability.

Foxp3-positive regulatory T cells (Tregs) are crucial for the maintenance of immune homeostasis and keep immune responses in check. Upon activation, Tregs are transferred into an effector state expressing transcripts essential for their suppressive activity, migration, and survival. However, it is not completely understood how different intrinsic and environmental factors control differentiation. Here, we present for the first time to our knowledge data suggesting that Treg-intrinsic expression of CD83 is essential for Treg differentiation upon activation. Interestingly, mice with Treg-intrinsic CD83 deficiency are characterized by a proinflammatory phenotype. Furthermore, the loss of CD83 expression by Tregs leads to the downregulation of Treg-specific differentiation markers and the induction of an inflammatory profile. In addition, Treg-specific conditional knockout mice showed aggravated autoimmunity and an impaired resolution of inflammation. Altogether, our results show that CD83 expression in Tregs is an essential factor for the development and function of effector Tregs upon activation. Since Tregs play a crucial role in the maintenance of immune tolerance and thus prevention of autoimmune disorders, our findings are also clinically relevant.

Population pharmacokinetics of vancomycin in critically ill patients receiving prolonged intermittent renal replacement therapy.

OBJECTIVES: The aim of this study was to describe the population pharmacokinetics of vancomycin during prolonged intermittent renal replacement therapy (PIRRT) in critically ill patients with acute kidney injury. METHODS: Critically ill patients prescribed vancomycin across two sites had blood samples collected during one to three dosing intervals during which PIRRT was performed. Plasma samples were assayed with a validated immunoassay method. Population pharmacokinetic analysis and Monte Carlo simulations were performed using Pmetrics®. The target vancomycin exposures were the area under the concentration-time curve within a 24-h period (AUC0-24)/minimum inhibitory concentration (MIC) ratio of 400 for efficacy and AUC0-24 700 for toxicity. RESULTS: Eleven critically ill patients (seven male) were enrolled and contributed 192 plasma samples. The patient's mean ± standard deviation (SD) age, weight and body mass index (BMI) were 57 ± 13 years, 98 ± 43 kg and 31 ± 9 kg/m2, respectively. A two-compartment linear model adequately described the data. The mean ± SD population pharmacokinetic parameter estimates were PIRRT clearance (CL) 3.47 ± 1.99 L/h, non-PIRRT CL 2.15 ± 2.07 L/h, volume of distribution of the central compartment (Vc) 41.85 ± 24.33 L, distribution rate constant from central to peripheral compartment 5.97 ± 7.93 per h and from peripheral to central compartment 5.29 ± 6.65 per h. Assuming a MIC of 1 mg/L, vancomycin doses of 25 mg/kg per day are suggested to be efficacious, whilst minimising toxic, exposures. CONCLUSIONS: This is the first population pharmacokinetic study of vancomycin in patients receiving PIRRT and we observed large pharmacokinetic variability. Empirically, weight-based doses that are appropriate for the duration of PIRRT, should be selected and supplemented with therapeutic drug monitoring.

High-sensitivity blood-based detection of breast cancer by multi photon detection diagnostic proteomics.

We have developed several new methods for blood-based cancer detection by diagnostic proteomics. Ultrasensitive methods of immunoassay using multiphoton-detection (IA/MPD) increase sensitivity by 200- to 1,000-fold (1 femtogram/mL). This has allowed the measurement of cancer biomarkers with very low concentrations in blood that could not be measured for full patient cohorts with conventional immunoassays. Sensitivity and specificity in cancer detection have been found to be potentiated by use of immunoassay panels which include tissue-specific cancer biomarkers as well as cytokines and angiogenic factors. The ultrasensitive immunoassays revealed that patient to patient variations in the concentrations of individual biomarkers in blood can extend over many orders of magnitude (up to six) and that the distributions of biomarker concentrations over patient cohorts are non-Gaussian. New methods of data analysis which correlate abundances of multiple, different biomarkers have been developed to deal with such data sets. Sensitivity and specificity of about 95% have been achieved for blood-based detection of breast cancer in pilot studies on 250 patients and 95 controls. Pilot studies indicate that this methodology may also allow differentiation of malignant breast cancer from benign lesions and can provide similar sensitivity and specificity for other epithelial cancers such as prostate cancer, ovarian cancer and melanoma. The methods developed for selection, application, and evaluation of very high sensitivity biomarker panels are expected to have general relevance for diagnostic proteomics.