LPS treatment “activates” PCs and PVM/Ms in the intra-strial fluid–blood barrier.

LPS treatment “activates” PCs and PVM/Ms in the intra-strial fluid–blood barrier. (A) and (B) Cochlear cross-sections show slight hydrops in LPS-treated animals (black arrows/stars). (C) A representative confocal 3D maximum projection shows normal, inactivated PCs in vivo (in transgenic mice with fluorescent labeled NG2, red) to have a flat and slender cell body. The cell morphology is clearly shown in the enlarged image from region of (a) in Fig 2C. (D) LPS stimulated PCs display a “prominent round” cell body in less physical contact with the strial capillary and release a large number of particles which can be easily seen in the enlarged image from region of (b) in Fig 2D (indicated by the arrow). (E) PVM/M distribution on strial capillaries, shown labeled with GS-IB4 in a control animal. Fig E (c) is an enlarged image from region of (c) in Fig 2E. The PVM/M enshrouds a capillary network with its slander dendritic branches (indicated by the arrow). (F) PVM/Ms in LPS-treated animals display a reduced amount of branching, as well as withdrawal of ramifications. PVM/Ms in LPS-treated animals are in less physical contact with capillaries. A subset of the PVM/Ms is activated, indicated by display of a terminal galactopyranosyl group on the membrane surface and binding with GS-IB4. Fig 2F (d) is an enlarged image from region of (c) in Fig 2F. Here the PVM/M is shown still surrounding the capillary network, but with withdrawal of dendritic branches (arrow). (G) Primary cell lines of cultured PCs are large, flat, stellate shaped cells, with a broadfilopod morphology. (H) LPS treatment for 48 hours causes PCs to branch and release a large number of particles. (I) Primary cell lines of cultured PVM/Ms under control conditions display a unique pattern of dendritic processes. GS-IB4 fluorescence in the control (non-LPS treated) cell line was undetectable. (J) Some perivascular resident macrophages are activated, displaying a terminal galactopyranosyl group on the membrane surface and binding the lectin Griffonia simplicifolia-IB4 (arrows, GS-IB4). The data show PCs and PVM/Ms are highly responsive to LPS. The control and LPS-treated groups show clear signs of morphological changes.