Pleural Fluid Volume: The pleural fluid volume was significantly greater after the intrapleural injection of SN than it was after the intrapleural injection of TL at each time point (Table 1). The amount of pleural fluid tended to increase with time in both groups.
IL-8: There were detectable levels of IL-8 in the pleural fluid after the intrapleural injection of both TL and SN. The highest level of pleural fluid IL-8 occurred in the SN group 6 h after injection, and this level was significantly higher than the levels occurring at 24 or 48 h after SN injection or at any time after the injection of TL (Table 2). The pleural fluid levels of IL-8 were comparable to those in serum, except for the level 6 h after SN injection, which was significantly higher than the serum level (Table 2).
VEGF: The pleural fluid VEGF levels tended to increase after the injection of both agents. The pleural fluid VEGF levels were significantly higher in the SN groups at 6 and 24 h.
Comparison Between Serum and Pleural Fluid IL-8 and VEGF Levels
IL-8 levels were significantly higher in the pleural fluid than in the serum at 6 h in the SN group. In contrast, IL-8 levels were significantly higher in the serum than in the pleural fluid at 48 h in both groups (Table 2). VEGF levels were significantly higher in the pleural fluid than in the serum at all time points for both agents (Table 2). The serum levels of VEGF were significantly correlated with the pleural fluid levels of VEGF in both groups (TL group: r = 0.74; p < 0.001; SN group: r = 0.72; p < 0.001) [Fig 6, 7]. In contrast, the serum levels of IL-8 did not correlate as well with the pleural fluid levels (TL group: r = 0.45; p = 0.04; SN group: r = 0.50; p = 0.03). website
The present study demonstrates that both TL and SN, when injected intrapleurally, induce an acute systemic inflammatory response. After 6 h, TL induced a predominant cellular response, with an increased blood WBC count and neutrophil percentage that decreased with time, equaling those of the control group after 48 h. The serum levels of VEGF also increased in the short term in animals injected with TL and remained elevated at 48 h after pleural injection.
Figure 6. Comparison of VEGF levels (pg/mL) in the serum and pleural fluid of TL-injected rabbits.
Figure 7. Comparison of VEGF levels (pg/mL) in the serum and pleural fluid of SN-injected rabbits.
Table 2—Comparison Between Serum and Pleural Fluid Levels of IL-8 and VEGF in TL and SN-Injected Rabbits
|Time||IL-8, pg/mL||VEGF, pg/mL|
|6 h||563 ± 202||882 ± 377||2,250 ± 3071||8,212 ± 1,951||51 ±14||196 ± 69||47 ±13||506 ± 100|
|24 h||954 ± 515||705 ± 304||1,512 ± 512||1,510 ± 340||55 ±5||514 ± 66||53 ± 9||718 ± 85|
|48 h||1,571 ± 366||737 ± 234§||2,064 ± 733||936 ±218||64 ±20||948 ± 246||57 ±9||1,045 ± 159|