High levels of pepsin, a digestive enzyme that is a marker for gastric aspiration, are associated with acute rejection of a lung transplant , according to researchers in the United Kingdom . This research provides further evidence that lung rejection may be caused by factors other than alloimmunity, the attack the body mounts to protect itself against foreign cells.
We think gastric aspiration [the taking of stomach fluids into the lung] may contribute to an overall injury to the transplanted lung, said Chris Ward, Ph.D., lead author of the study. This pattern of injury may be similar to rejection or increase the risk for further rejection.
The study included 36 lung transplant recipients, 17 subjects with normal lung function but unexplained cough who served as disease controls for the study, and 4 normal, nonsmoking control subjects. The researchers determined pepsin levels in all the subjects using bronchoalveolar lavage (BAL)
Our primary finding was that, compared with control subjects, wrote the researchers, BAL pepsin levels were elevated in stable lung transplant recipients, subjects with acute rejection, and subjects with bronciolitis obliterans [a common manifestation of lung transplant rejecton]. Our secondary finding was that the highest levels of pepsin appeared in the transplant recipients with clinically significant acute rejection (grade A2 or greater).
These findings support the growing recognition that gastroesophageal reflux (GER) is a potential cause for post-transplant lung injury and other airway and lung diseases. Although none of the transplant patients were formally evaluated for GER, nearly all were treated with acid suppression medications, which is standard therapy after lung transplantation.