Current and prospective treatments of obliterative bronchiolitis:

Chlamydia pneumoniae infection after lung transplantation

BACKGROUND

Chlamydia pneumoniae is established as a common agent of acute respiratory tract infection and has been implicated in the pathogenesis of asthma and chronic obstructive pulmonary disease. Airway disease is a prominent cause of morbidity and mortality after lung transplantation. We investigated the role of C pneumoniae as a pulmonary pathogen after lung transplantation.

METHODS

Eighty lung transplant recipients underwent 232 bronchoscopies with bronchoalveolar lavage with or without transbronchial lung biopsy during 1 year for surveillance of rejection and infection, or where clinically indicated.

RESULTS

C pneumoniae was detected using nested polymerase chain reaction in 9 of 36 (25%) recipients studied within 30 days of lung transplantation, 3 of whom remained positive on repeat lavage and died from airway disease in the first year post-operatively. By comparison, all 27 recipients with negative lavage survived >1 year. Lavage was positive for C pneumoniae in 18 of 71 (25%) recipients studied >30 days after lung transplantation, 5 of whom had pneumonia and 8 of whom had bronchiolitis obliterans syndrome. Eleven also had acute pulmonary allograft rejection.

CONCLUSIONS

Persistent infection with C pneumoniae (whether donor-derived, de novo or re-activated) appears deleterious to pulmonary allograft function and is associated with early mortality, rejection and bronchiolitis obliterans syndrome after lung transplantation. A trial of empiric antibiotic therapy for C pneumoniae may therefore be warranted in the attempt to prevent progressive inflammatory airway disease.

Everolimus and mycophenolate mofetil are potent inhibitors of fibroblast proliferation after lung transplantation1

BACKGROUND

Dysregulated fibroblast proliferation is thought to play an important role in the progression of bronchiolitis obliterans (BO) after lung transplantation. Augmented immunosuppression is often used to treat BO. We investigated the effect of methylprednisolone (mPRED), cyclosporine A (CsA), tacrolimus (FK506), azathioprine (AZA), mycophenolate mofetil (MMF), and everolimus (rapamycin derivative [RAD]) on the proliferative capacity of fibroblasts cultured from transbronchial biopsies of lung transplant recipients.

METHODS

Primary cultures of human lung fibroblasts were obtained from 14 transbronchial biopsies of lung transplant recipients. Subconfluent cells were serum starved for 24 hr followed by growth stimulation in the presence or absence of the respective drug in six concentrations ranging as follows: 0.01 to 100 mg/L for mPRED; 0.01 to 50 mg/L for CsA and AZA; 0.001 to 5 mg/L for FK506 and MMF; and 0.00001 to 1 mg/L for RAD. Proliferation was quantified by [3H]thymidine incorporation and direct cell count. A toxic drug effect was excluded by trypan blue.

RESULTS

Drug concentrations (mg/L) causing a 50% inhibition of fibroblast proliferation were mPRED 4; CsA 20; FK506 0.3; AZA 7; MMF 0.3; and RAD 0.0006. Drug concentrations (mg/L) causing inhibition of fetal bovine serum-induced proliferation were mPRED 60; CsA 45; FK506 3; AZA 35; MMF 1; and RAD 0.003.

CONCLUSIONS

RAD and MMF were the most potent antifibroproliferative drugs and were effective at concentrations achieved clinically, supporting their use for the treatment of patients with early BO. Our method holds promise as an in vitro model to assess the likely in vivo responses of human lung fibroblasts to specific immunosuppressive drugs.