[Effects of glucocorticoids on tuberculous pleural effusion: experiment with rats]

To explore the effects of systemic glucocorticoid treatment on tuberculous pleural effusion.

Ninety Wistar rats were intrapleurally injected with 0.03 mg of standard human Mycobacterium tuberculosis to establish models of tuberculous pleural effusions and then were randomly divided into 2 equal groups both without anti-tuberculosis treatment: glucocorticoids group (GG) undergoing intramuscular injection of 0.3 mg triamcinolone acetonide in the right thigh 24 h after intrapleural injection, and control group (CG) received nothing as control. 8, 24, 32, and 48 hours, and 3, 5, 7, 10, and 15 days after intramuscular injection 5 rats from each group were killed. The thorax was opened, the amount of pleural effusion (PE) was recorded, and the pleural cavity, histopathology of pleura and lung parenchyma were examined. The white blood cell (WBC) count and differential leukocyte count, and levels of total protein (TP), glucose (GLU), and lactic dehydrogenase (LDH) in the PE were determined. Bioassays were used to detect the PE levels of soluble intercellular adhesion molecule-1 (sICAM-1), transforming growth factor beta1 (TGF-beta1), and interferon gamma (IFN-gamma).

The PE volumes of GG 8 - 48 h after the intramuscular injection were significantly lower than those of CG (P < 0.05, P < 0.01), and PE completely disappeared on day 3. The WBC in PE 24 - 48 h after and the percentages of neutrophils 8 - 48 h after the intramuscular injection of GG were all significant lower than those of CG (all P < 0.01). The TP levels 32 and 48 h after the intramuscular injection of GG were both significantly higher than those of CG (both P < 0.01). The LDH level of GG within 24 h after the intramuscular injection was significantly lower than that of CG (P < 0.01). Both the sICAM-1 and TGF-beta1 levels of GG were higher 8 h after the intramuscular injection, but lower 48 h after the intramuscular injection than those of CG (both P < 0.01). The IFN-gamma levels 8 - 48 h after the intramuscular injection of GG were all higher than those of CC (all P < 0.01). The IFN-gamma/TGF-beta1 ratios at different time points of GG were all higher than those of CG, and there were significant differences in those 8 - 48 h after the intramuscular injection between these 2 groups (all P < 0.01). Pathologically, the mean thickness of pleura in GG was significantly less than that in CG. Congestion and edema in subpleural and pulmonary interstitium were less in GG than in CG.

Early use of glucocorticoids helps reduce the inflammatory response in pleural cavity in tuberculous pleurisy accelerate the absorption of pleural effusion and decrease the thickness of pleura.