COPD is a leading cause of morbidity and mortality in Europe and the US (ranked 3^rd and 4^th respectively). The main risk factors for COPD are smoking and occupational exposure to particulate matter. It is well known that cigarette smoke contains free radicals (Rahman, 1996) and as such causes an oxidant based insult to the lung. We have previously shown that CSE is able to activate THP-1 monocytes to release Interleukin-8 (IL-8) and that CSE is capable of synergising with IL-1ß in this release (Walters, 2003). Here we have compared the action of two anti-oxidants, Glutathione (GSH) and N-acetyle cysteine (NAC) on the release of IL-8 from THP-1 monocytes treated with CSE and IL-1ß alone and a combination of the two.

For 100% solutions, cigarette smoke was drawn from four cigarettes (full strength Marlboro) through 100mls of RPMI 1640 to produce our strongest smoke solution. The 'strength' of each smoke extract made was assessed by measuring nitrite levels using the Greiss reaction (Bishop-Bailey et al., 1997). Cells were treated for a period of 24hrs when supernatants were collected and assayed for IL-8 as described previously (Walters, 2003).

10% CSE and 1ng ml^-1IL-1ß both caused a significant release of IL-8 over basal (25±3 pg ml^-1) Co-treatment of THP-1's with both 10% CSE and 1ng ml^-1 IL-1ß caused a synergistic release of IL-8 (see figures). Treatment with either GSH or NAC (10^-5 to 10^-3M) caused no significant decrease in basal release of IL-8 (data not shown).

GSH (fig 1A) (10^-3) caused a significant decrease in IL-8 release from cells treated with 10% CSE () alone (p= <0.001 N=3), and in those treated with a combination of 10% CSE and 1ng ml^-1 IL-1ß (fig 1B) (p= <0.001 N=3). GSH did not cause any significant change in IL-8 from cells stimulated with 1ng ml-1 IL-1ß (fig 1A). NAC (fig 2A) caused a significant decrease (p=<0.001 N=3) in IL-8 release from cells treated with 10% CSE () alone and in those treated with a combination of 10% CSE and 1ng ml^-1 IL-1ß (fig 2B) (p= <0.001 N=3). GSH did not cause any significant change in IL-8 from cells stimulated with 1ng ml^-1 IL-1ß (fig 2A).

Figure 1

Figure 2

10% CSE and IL-1ß. However neither had a significant effect on IL-1ß induced IL-8 release from these cells. These data show quite clearly that the mechanism behind cigarette smoke induced IL-8 release in these cells is an oxidant driven one and point to this mechanism being a possible target for therapeutic agents.

Rahman, I., Smith, C.A.D., Lawson, M.F., et al (1996). FEBS Letters 396(1):21-25.
Walters M.J, & J.A. Mitchell (2003) Brit. J. Pharmcol. ,138, 44P.
Bishop-Bailey, D., Larkin, S.L., Williams, T.J et al. (1997), Brit. J. Pharmcol. 121, 125-133.

This study was funded by an Industrial collaborative grant between the MRC and Yamanouchi.