Does tumour necrosis factor-alpha inhibitor infliximab induce histological resolution of pulmonary sarcoid granulomas?

BACKGROUND

Sarcoid granuloma formation involves the orchestration of cytokines and chemokines, which modulate the host's immune response to the antigen stimulus. The release of cytokines enhances expression of the pro-inflammatory cytokine tumour necrosis factor-alpha (TNF), which plays a crucial role in the formation of sarcoid granuloma, being released from T-lymphocytes and alveolar macrophages.

OBJECTIVE

The aim of this study was to evaluate the effect of infliximab in a case of pulmonary sarcoidosis using a histological approach.

MATERIALS AND

METHODS

A 44-year-old man with biopsy verified chronic pulmonary sarcoidosis being resistant to treatment with corticosteroids and cell cycle inhibitors. Persisting disease activity was confirmed by declining lung function tests and a positive fluorine-18-fluorodeoxyglucose-positron emission tomography scan. The patient was treated with a single course of infliximab 3-mg/kg body weight; 11 days later, a single lung transplantation was performed. Immunohistological staining with the macrophage marker CD68 was performed on lung tissue and mediastinal lymph node tissue from both the initial diagnostic evaluation (prior to infliximab) as well as from the explanted lung (after infliximab).

RESULTS

Biopsy specimens from lung and mediastinal lymph nodes prior to infliximab demonstrated sarcoid granulomas, and staining with CD68 showed dense infiltration by macrophages (epithelioid cells) in the central part of the granulomas. In contrast, biopsies from the explanted lung after infliximab demonstrated acellular sarcoid granulomas with central amorphous masses, and staining with CD68 showed complete absence of macrophages.

CONCLUSIONS

In this patient, the TNF inhibitor infliximab appeared to induce resolution of sarcoid granulomas starting with disappearance of macrophages probably caused by cell lysis or apoptosis.