Cross-talk between macrophages, smooth muscle cells, and endothelial cells in response to cigarette smoke: the effects on MMP2 and 9.

We hypothesized that matrix metalloproteinase secretion in response to cigarette smoke is modulated by cross-talk between resident cells within the aorta, namely, aortic smooth muscles, endothelial cells, and infiltrating macrophages, and this may be crucial for in vivo formation/progression of abdominal aortic aneurysm (AAA). Cigarette smoke extract (CSE) was applied to rat aortic smooth muscle (RASMC), endothelial (RAEC) or RAW cells, and conditioned media (CSE-CM) collected. Fresh cells were treated with CSE-CM for 24 h and then maintained in serum-free medium (SFM) for 72 h to analyze MMP2 and MMP9 in media by zymography and the ratio (pS/pJ) of phospho-Stat3 (pStat3) and phospho-Jak2 (pJak2) inside the cells by Western blot. We observed that CSE-CM from RAW and RAEC increased MMP9 by 200 and 17 %, respectively, in RASMC and also increased pS/pJ ratio (305 and 228 %, respectively) in RASMC. RAW cell-derived CSE-CM induced RAEC to produce moderate amounts of MMP2 (17 %), MMP9 (30 %), and a 137 % increase in pS/pJ. RAW cells receiving unstimulated CM from RASMC and RAEC produced significant amounts of MMP9 (128 and 155 %, respectively) and increased pS/pJ (45 and 1283 %, respectively). CSE-CM from RASMC and RAEC induced significant production of MMP9 from RAW cells (237 and 162 %, respectively) and increase in pS/pJ ratios (1348 and 1494 %, respectively). This is the first in vitro study demonstrating cigarette smoke extract-mediated differential interactions between resident cells in the aorta leads to altered modulation of signaling molecules that may be vital for AAA formation under in vivo conditions.