I am happy to share gr-limesdr plugin based on LimeSDR API for GNU Radio. This allows to communicate with LimeSDR boards from GNU Radio directly via LimeSDR API, without additional software layers (like UHD). Check the Wiki page for installation instructions, links and documentation:
https://wiki.myriadrf.org/Gr-limesdr_Plugin_for_GNURadio
LimeSDR-USB and LimeSDR-Mini boards supported under Linux OS for now.
Note please, that it is beta version for now, hence comments and notes are welcome. Thank you all for your support!