Prophylactic treatment with azithromycin mitigates the impact of human rhinovirus infection in lung transplant recipients, Australian research shows.

A WA study using large and small airway epithelial cells from five lung allograft recipients has confirmed rhinovirus caused significant cytotoxicity in both cell cultures.

Viral infection at low titres in large airway epithelial cells significantly reduced cell viability by about 20% at 24 hours and even further at 48 hours or at higher viral titres. There was a less pronounced effect on small airway epithelial cells.

The study found viral infection also induced programmed cell death in both large and small airway epithelial cells.

However pretreatment with azithromycin led to a significant reduction in viral replication – about a 60% reduction in small airway cells and about a 25% reduction in the large airway cells.

Azithromycin also significantly reduced inflammation caused by viral infection with sizeable reductions in chemokines IL-8 (by 64-68%), IL-6 (by 130-154%) and RANTES (by 593-1465%).

The study investigators led by Associate Professor Anthony Kicic, head of airway epithelial research at Telethon Kids Institute, Perth, said the findings were consistent with those from other respiratory patient groups including cystic fibrosis and asthma.

“Collectively, we show that rhinovirus infection drives cell death and inflammation in the lung, and that prophylactic treatment with azithromycin can mitigate these detrimental responses,” they wrote in Respirology.

They noted that azithromycin was widely used due to its anti-inflammatory and immunomodulatory properties in addition to its antibacterial properties.

“The current clinical practice guidelines for lung allograft recipients suggest that introduction of prophylactic azithromycin treatments in patients with suspected BOS [bronchiolitis obliterans syndrome] reduces disease progression.”

“Our results demonstrate that pretreatment with azithromycin was effective in reducing viral replication and the production of sentinel inflammatory cytokines including IL-6, IL-8 and RANTES.”

“Collectively, these findings provide supportive evidence for the potential prescription of azithromycin as prophylactic treatment in lung allograft patients to mitigate the impact of RV infection and improve longevity of the allograft.”