Treatment updates in post-infectious bronchiolitis obliterans

Anna Marie Nathan
University Malaya Medical Centre, Kuala Lumpur, Malaysia

Until today, there isn’t a clearly defined nor accepted treatment protocol for PiBO. This perhaps due to the unequal distribution of occurrence of PIBO, happening mainly in South America, China and Asia, suggesting a possible genetic predisposition.

As the pathophysiology of post-infectious bronchiolitis obliterans is an overly brisk inflammatory response that fails to stop, majority of the treatment is aimed at controlling inflammation (particularly neutrophilic) and proinflammatory cytokines e.g. IL‐1β, IL‐6, and IL‐8.

Steroids have been investigated, though majority of the studies are retrospective and/or small.

• Early use (within 3 weeks to 3 months of illness) of pulse IV Methylprednisolone at doses > 10 mg/kg/day x 3 days. However, there is no knowledge of how many cycles of corticosteroid should be given and for how long
• Inhaled corticosteroids (Budesonide 500mcgs bd) for 6 months may improve lung function.
• Fluticasone, Azithromycin + Montelukast or FAM therapy: this has been extrapolated from treatment of Bronchiolitis Obliterans Syndrome (post-transplant) although there is little evidence to support its use in PiBO. There are studies from China that use Inhaled Budesonide at 1 mg bd instead of Fluticasone, to the FAM therapy and show some improvements in lung function and growth.
• Oral prednisolone 1.5mg/kg/day x 1 month and slowly taper off by 6 months has also been used.

As Azithromycin has been recognised to have anti-neutrophilic activity and anti-IL 6,8 and TNF, it has also been used: dose 5 mg/kg/EOD. However, once again the evidence is lacking.

Supportive care cannot be underestimated: includes administering oxygen as needed, bronchodilators, respiratory physiotherapy, antibiotics in cases of acute respiratory infections, diuretics in some patients, immunizations for pneumococcus and influenza, adequate nutrition, and avoidance of tobacco smoke or other inhaled drugs.

Research into the role of microRNAs(miRNAs) is promising and upcoming, demonstrating its role in dysregulated inflammation, and this may lead to more effective therapeutic options.