A 60-year old male has a long standing history of breathlessness. He has been a heavy smoker since the age of 20 years. Physical examination reveals an anxious male who is emaciated, puffing for breath but is not cyanosed. The chest is barrels shaped. The primary pathology of the lung in this patient is associated with which of the following pathogenetic mechanisms?

From the history and clinical findings,the probable diagnosis is chronic obstructive pulmonary disease-emphysematous type.Severe alpha1 antitrypsin (protease inhibitor) deficiency is a proven genetic risk factor for COPD.The unopposed action of elastolytic proteases lead to destruction and enlargement of gas-exchanging air spaces,thus leading to the development of emphysema. Ref:Harrison's medicine-18th edition,page no:2152,2155.