CD8α(+) dendritic cells are an obligate cellular entry point for productive infection by Listeria monocytogenes.

CD8α(+) dendritic cells (DCs) prime cytotoxic T lymphocytes during viral infections and produce interleukin-12 in response to pathogens. Although the loss of CD8α(+) DCs in Batf3(-/-) mice increases their susceptibility to several pathogens, we observed that Batf3(-/-) mice exhibited enhanced resistance to the intracellular bacterium Listeria monocytogenes. In wild-type mice, Listeria organisms, initially located in the splenic marginal zone, migrated to the periarteriolar lymphoid sheath (PALS) where they grew exponentially and induced widespread lymphocyte apoptosis. In Batf3(-/-) mice, however, Listeria organisms remain trapped in the marginal zone, failed to traffic into the PALS, and were rapidly cleared by phagocytes. In addition, Batf3(-/-) mice, which lacked the normal population of hepatic CD103(+) peripheral DCs, also showed protection from liver infection. These results suggest that Batf3-dependent CD8α(+) and CD103(+) DCs provide initial cellular entry points within the reticuloendothelial system by which Listeria establishes productive infection.

Surfactant-modified beta-TCP: structure, properties, and in vitro remineralization of subsurface enamel lesions.

A hybrid material comprised of beta-tricalcium phosphate (beta-TCP) and sodium lauryl sulfate (SLS) was prepared using a mechanochemical process, examined using particle size analysis, IR spectroscopy, (31)P, (23)Na, and (13)C solid-state NMR spectroscopy, and calcium dissolution experiments, and probed for in vitro remineralization of subsurface enamel lesions. Our results suggest that while the (31)P environments of beta-TCP remain unchanged during solid-state processing, there is noticeable shifting among the SLS (23)Na and (13)C environments. Therefore, given the structure of beta-TCP, along with our IR examinations and calcium dissolution isotherms, SLS appears to interface strongly with the cation deficient C(3) symmetry site of the beta-TCP hexagonal crystal lattice with probable emphasis placed on the underbonded CaO(3) polyhedra. To demonstrate the utility of the surface-active TCP material in dental applications, we combined the TCP-SLS with 5,000 ppm F (NaF) and evaluated the remineralization potential of subsurface enamel lesions via an in vitro remineralization/demineralization pH cycling dental model. Using surface and longitudinal microhardness measurements, the TCP-SLS plus 5,000 ppm F system was found to significantly boost remineralization of subsurface enamel lesions, with microhardness values increasing up to 30% greater than fluoride alone.

Preparation, characterization and in vitro efficacy of an acid-modified beta-TCP material for dental hard-tissue remineralization.

A blended material composed of beta-tricalcium phosphate (beta-TCP) and fumaric acid (FA) was prepared using a mechanochemical process. The structure and properties of the TCP-FA material was probed using particle size analysis, infrared, (31)P and (13)C solid-state nuclear magnetic resonance (NMR) spectroscopy, powder X-ray diffraction and calcium bioavailability. NMR studies showed that orthophosphate environments within beta-TCP remain largely unaffected in the presence of FA during mechanochemical processing; alternately, (13)C data indicated the carboxylic groups of FA are strongly affected during processing with beta-TCP. X-ray results reveal beta-TCP diffraction plane shifting with lattice contractions likely arising at the C(3) symmetry site. While milled beta-TCP (mTCP) produces a higher flux of bioavailable calcium relative to native beta-TCP, the mechanochemical conditioning of TCP-FA generates more than seven times the level of ionic calcium relative to mTCP. Collectively, the results from these studies indicate FA interfaces with calcium oxide polyhedra of the beta-TCP hexagonal crystal lattice, especially with the underbonded CaO(3) cluster manifested within the C(3) symmetry site of the beta-TCP motif. An in vitro remineralization/demineralization pH cycling dental model was then used to assess the potential of the TCP-FA material in reversing early stage non-cavitated enamel lesions. Characterization of the remineralization via surface and longitudinal microhardness measurements demonstrated that the TCP-FA material provides statistically superior remineralization relative to milled and native beta-TCP.