Activation of complement component 3 is associated with airways disease and pulmonary emphysema in alpha-1 antitrypsin deficiency

What is it about?

What is the key question? We questioned whether alpha-1 antitrypsin (AAT) binding to plasma constituents could regulate their activation, and in AAT deficiency (AATD), exploit this binding event to gain further insight into the pathogenesis of emphysema. What is the bottom line? AAT binds directly to complement component C3, and in AATD, elevated levels of the complement activation product C3d were detected in plasma and airway samples, and correlated with airway obstruction and radiographic pulmonary emphysema. Why read on? Intravenous AAT augmentation therapy normalized plasma AAT levels in vivo, and concomitantly reduced circulating levels of C3d, indicating that C3d may serve as a determinant of therapeutic efficacy for emerging therapies in AATD.

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