Hot Topic: [The Role of Arginase in Lung Disease (Guest Editor: Hartmut Grasemann)]

Abstract

Nitric oxide synthases (NOSs) metabolize the amino acid L-arginine to form nitric oxide (NO) and L-citrulline. NO is involved in a broad spectrum of processes in the lungs and airways, including perfusion, ventilation, inflammation, infection and airway clearance. The activity of NOS can change in response to, for instance, inflammatory stimuli that can alter enzyme expression. In addition, NOS activity can be regulated post-transcriptionally by specific endogenous NOS inhibitors, such as asymmetric dimethylarginine (ADMA), but also by substrate limitation. The arginase isoenzymes decrease NO production by reducing the availability of L-arginine for NOS [1]. There is accumulating evidence that disturbances of the balance between the L-arginine metabolizing enzymes can result in both acute and chronic pathological changes. Reduced substrate availability for NOS affects the regulation of airways smooth muscle tone for instance in asthma methacholine responsiveness, and downstream products of arginase activity i.e., L-proline and the polyamines, may contribute to lung fibrosis and airway