Artery Tertiary Lymphoid Organs Control Aorta Immunity and Protect against Atherosclerosis via Vascular Smooth Muscle Cell Lymphotoxin ß Receptors.

Tertiary lymphoid organs (TLOs) emerge during nonresolving peripheral inflammation, but their impact on disease progression remains unknown. We have found in aged Apoe(-/-) mice that artery TLOs (ATLOs) controlled highly territorialized aorta T cell responses. ATLOs promoted T cell recruitment, primed CD4(+) T cells, generated CD4(+), CD8(+), T regulatory (Treg) effector and central memory cells, converted naive CD4(+) T cells into induced Treg cells, and presented antigen by an unusual set of dendritic cells and B cells. Meanwhile, vascular smooth muscle cell lymphotoxin ß receptors (VSMC-LTßRs) protected against atherosclerosis by maintaining structure, cellularity, and size of ATLOs though VSMC-LTßRs did not affect secondary lymphoid organs: Atherosclerosis was markedly exacerbated in Apoe(-/-)Ltbr(-/-) and to a similar extent in aged Apoe(-/-)Ltbr(fl/fl)Tagln-cre mice. These data support the conclusion that the immune system employs ATLOs to organize aorta T cell homeostasis during aging and that VSMC-LTßRs participate in atherosclerosis protection via ATLOs.

In vivo real-time multiphoton imaging of T lymphocytes in the mouse brain after experimental stroke.

BACKGROUND AND PURPOSE: To gain a better understanding of T cell behavior after stroke, we have developed real-time in vivo brain imaging of T cells by multiphoton microscopy after middle cerebral artery occlusion. METHODS: Adult male hCD2-GFP transgenic mice that exhibit green fluorescent protein-labeled T cells underwent permanent left distal middle cerebral artery occlusion by electrocoagulation (n=6) or sham surgery (n=6) and then multiphoton laser imaging 72 hours later. RESULTS: Extravasated T cell number significantly increased after middle cerebral artery occlusion versus sham. Two T cell populations existed after middle cerebral artery occlusion, possibly driven by 2 T cell subpopulations; 1 had significantly lower and the other significantly higher track velocity and displacement rate than sham. CONCLUSIONS: The different motilities and behaviors of T cells observed using our imaging approach after stroke could reveal important mechanisms of immune surveillance for future therapeutic exploitations.

Fatty acid and phospholipid chlorohydrins cause cell stress and endothelial adhesion.

The oxidation of low-density lipoprotein (LDL) is thought to contribute to atherogenesis, which is an inflammatory disease involving activation of phagocytic cells. Myeloperoxidase, an enzyme which is able to produce hypochlorous acid (HOCl), is released from these phagocytic cells, and has been found in an active form in atherosclerotic plaques. HOCl can oxidize both the lipid and protein moiety of LDL, and HOCl-modified LDL has been found to be pro-inflammatory, although it is not known which component is responsible for this effect. As HOCl can oxidize lipids to give chlorohydrins, we hypothesized that phospholipid chlorohydrins might have toxic and pro-inflammatory effects. We have formed chlorohydrins from fatty acids (oleic, linoleic and arachidonic acids) and from phospholipids (stearoyl-oleoyl phosphatidylcholine, stearoyl-linoleoyl phosphatidylcholine and stearoyl-arachidonoyl phosphatidylcholine), and investigated various biological effects of these oxidation products. Fatty acid and phospholipid chlorohydrins were found to deplete ATP levels in U937 cells in a concentration-dependent manner, with significant effects observed at concentrations of 25 microM and above. Low concentrations (25 microM) of stearoyl-oleoyl phosphatidylcholine and stearoyl-arachidonoyl phosphatidylcholine chlorohydrins were also found to increase caspase-3 activity. Finally, stearoyl-oleoyl phosphatidylcholine chlorohydrin increased leukocyte adhesion to artery segments isolated from C57Bl/6 mice. These results demonstrate potentially harmful effects of lipid chlorohydrins, and suggest that they may contribute to some of the pro-inflammatory effects that HOCl-modified low density lipoprotein has been found to induce.

Phospholipid chlorohydrins cause ATP depletion and toxicity in human myeloid cells.

Chlorohydrins of stearoyl-oleoyl phosphatidylcholine (SOPC), stearoyl-linoleoyl phosphatidylcholine, and stearoyl-arachidonyl phosphatidylcholine were incubated with cultured myeloid cells (HL60) for 24 h, and the cellular ATP level was measured using a bioluminescent assay. The chlorohydrins caused significant depletion of cellular ATP in the range 10-100 microM. The ATP depletion by the phospholipid chlorohydrins was slightly less than that of 4-hydroxy-2-nonenal, but greater than that of hexanal, trans-2-nonenal, and autoxidised palmitoyl-arachidonoyl phosphatidylcholine. SOPC chlorohydrin was also found to cause loss of viability in U937 cells, and thus phospholipid chlorohydrins could contribute to the formation of a necrotic core in advanced atherosclerotic lesions.