Transforming growth factor beta2 induced pleurodesis is not inhibited by corticosteroids

Talc and tetracyclines induce pleurodesis by directly injuring the pleura. The injury results in intense inflammation which subsequently leads to fibrosis. Corticosteroids can inhibit talc pleurodesis by reducing the inflammatory process. We hypothesised that transforming growth factor beta2 (TGFbeta2), a fibrogenic cytokine with immunomodulatory functions, could induce effective pleurodesis without generating significant pleural inflammation and therefore remain effective despite co-administration of corticosteroids.

Thirty rabbits were divided into two groups. Rabbits in the steroid group received weekly intramuscular injections of triamcinolone diacetate (0.8 mg/kg). Ten rabbits in each group were given 5.0 microg TGFbeta2 intrapleurally via a chest tube while the remaining five received 1.7 microg TGFbeta2. Pleurodesis was graded macroscopically after 14 days from 1 (none) to 8 (>50% symphysis).

TGFbeta2 produced excellent pleurodesis at both 5.0 microg and 1.7 microg doses. The pleural effusions produced after the injection were low in all inflammatory markers. No significant differences were seen between the steroid group and controls in macroscopic pleurodesis scores (7.2 (1.3) v 7.1 (1.2)), levels of inflammatory markers in the pleural fluids (leucocyte 1107 (387)/mm(3) v 1376 (581)/mm(3); protein 3.1 (0.3) mg/dl v 2.9 (0.3) mg/dl, and LDH 478 (232) IU/l v 502 (123) IU/l), and the degree of microscopic pleural fibrosis and pleural inflammation.

TGFbeta2 can induce effective pleurodesis and remains effective in the presence of high dose parenteral corticosteroids.