TABLE 2.

Chronic Inflammation and Fibrosis in TCDD-Treated SiO₂–Exposed Mice

	Wet weight				Hydroxyproline
	Vehicle + peanut oil	Vehicle + TCDD	Silica + peanut oil	Silica + TCDD	Vehicle + peanut oil	Vehicle + TCDD	Silica + peanut oil	Silica + TCDD
Sequential	126.0 ± 3.7	109.7 ± 7.0	164.8 ± 12.2*	171.0 ± 21.0*	29.38 ± 0.9	27.93 ± 0.3	37.90 ± 1.5*	42.03 ± 0.9*
Concomitant	102.7 ± 5.0	107.9 ± 15.0*	145.8 ± 3.4*	140.0 ± 5.5*	22.09 ± 1.0	21.25 ± 0.7	29.86 ± 1.2*	32.65 ± 1.3*

Notes. Neither sequential nor concomitant exposure to TCDD altered SiO₂-induced increases in wet weight and collagen deposition in the lungs of C57Bl/6 mice. In the sequential exposure paradigm, mice were exposed to 25 μl vehicle or 1 mg SiO₂ suspended in vehicle once a week for 4 weeks prior to weekly vehicle (200 μl peanut oil) or TCDD (10 mg/kg) oral gavage for the next 8 weeks. In the concomitant exposure paradigm, mice were gavaged weekly with vehicle or TCDD, beginning 1 day prior to being exposed to vehicle or SiO₂ suspended in vehicle as described in Supplementary figure 1. Values are means ± SEM.

^*p < 0.05 compared with vehicle controls, n = 5–6.