All Publications


  • Cutting the Gordian Knot of the Microbiota MOLECULAR CELL Vasquez, K. S., Shiver, A. L., Huang, K. 2018; 70 (5): 765–67

    Abstract

    The gut microbiota plays a central role in human health. Studies by Tramontano et al. (2018) and Maier et al. (2018) improve our understanding of the metabolism and pharmaceutical impact of human gut bacteria through high-throughput screening of growth in the presence of different nutrients and drugs, respectively.

    View details for PubMedID 29883604

  • Commensal Microbes and Hair Follicle Morphogenesis Coordinately Drive Treg Migration into Neonatal Skin CELL HOST & MICROBE Scharschmidt, T. C., Vasquez, K. S., Pauli, M. L., Leitner, E. G., Chu, K., Truong, H., Lowe, M. M., Rodriguez, R. S., Ali, N., Laszik, Z. G., Sonnenburg, J. L., Millar, S. E., Rosenblum, M. D. 2017; 21 (4): 467-?

    Abstract

    Regulatory T cells (Tregs) are required to establish immune tolerance to commensal microbes. Tregs accumulate abruptly in the skin during a defined window of postnatal tissue development. However, the mechanisms mediating Treg migration to neonatal skin are unknown. Here we show that hair follicle (HF) development facilitates the accumulation of Tregs in neonatal skin and that upon skin entry these cells localize to HFs, a primary reservoir for skin commensals. Further, germ-free neonates had reduced skin Tregs indicating that commensal microbes augment Treg accumulation. We identified Ccl20 as a HF-derived, microbiota-dependent chemokine and found its receptor, Ccr6, to be preferentially expressed by Tregs in neonatal skin. The Ccl20-Ccr6 pathway mediated Treg migration in vitro and in vivo. Thus, HF morphogenesis, commensal microbe colonization, and local chemokine production work in concert to recruit Tregs into neonatal skin, thereby establishing this tissue Treg niche early in life.

    View details for DOI 10.1016/j.chom.2017.03.001

    View details for PubMedID 28343820

  • Toward a Droplet-Based Single-Cell Radiometric Assay Analytical Chemistry Gallina, M. G., Kim, T., et al 2017: 6472-6481

    Abstract

    Radiotracers are widely used to track molecular processes, both in vitro and in vivo, with high sensitivity and specificity. However, most radionuclide detection methods have spatial resolution inadequate for single-cell analysis. A few existing methods can extract single-cell information from radioactive decays, but the stochastic nature of the process precludes high-throughput measurement (and sorting) of single cells. In this work, we introduce a new concept for translating radioactive decays occurring stochastically within radiolabeled single-cells into an integrated, long-lasting fluorescence signal. Single cells are encapsulated in radiofluorogenic droplets containing molecular probes sensitive to byproducts of ionizing radiation (primarily reactive oxygen species, or ROS). Different probes were examined in bulk solutions, and dihydrorhodamine 123 (DHRh 123) was selected as the lead candidate due to its sensitivity and reproducibility. Fluorescence intensity of DHRh 123 in bulk increased at a rate of 54% per Gy of X-ray radiation and 15% per MBq/ml of 2-deoxy-2-[18F]-fluoro-d-glucose ([18F]FDG). Fluorescence imaging of microfluidic droplets showed the same linear response, but droplets were less sensitive overall than the bulk ROS sensor (detection limit of 3 Gy per droplet). Finally, droplets encapsulating radiolabeled cancer cells allowed, for the first time, the detection of [18F]FDG radiotracer uptake in single cells through fluorescence activation. With further improvements, we expect this technology to enable quantitative measurement and selective sorting of single cells based on the uptake of radiolabeled small molecules.

    View details for DOI 10.1021/acs.analchem.7b00414

    View details for PubMedCentralID PMC5480233