Two Proteins For The Diagnosis Of Lung Diseases

200 different diseases

Lungfunction pathology takes in some 200 diseases which have muchradiological and pathological data in common, and which can greatlyshorten the life of the patient, the last resort being a lungtransplant. Amongst these diseases, the most common are theinterstitial pneumonias, more popularly known as pulmonary fibrosis.

Ahistological characteristic common to fibroproliferative alterations,states Ana Echegoyen, is the structural remodelling of the lung due tothe uncontrolled deposition of collagen tissue at the lung intersticesthus leading to pulmonary fibrosis. This fibrosis may be produced bytwo different mechanisms, interstitial fibrosis and intra-alveolarfibrosis, the latter being key in the structural remodelling of thelung.

The study was then based on two, non-collagenous proteinsfrom the extra-cellular matrix of the pulmonary interstices,fibronectin and tenascin in different fibroproliferative processes ofalveolar damage.

More reliable diagnoses

So,fibronectin is a protein from the extra-cellular matrix present inhealthy pulmonary interstices the expression of which augments withboth acute as well as chronic pulmonary damage and, together withcollagen, is an essential constituent of stable fibrous tissue inchronic lung damage.

Tenascin is a protein of the extra-cellularmatrix absent in healthy lungs which appears in the very initial stagesof pulmonary aggression, maintaining its presence during the process offibrogenesis and decreasing when the tissue fibrosis is alreadyestablished. This pattern of expression suggests that tenascin is aregulatory, non-structural protein of the acute stage that participatesin the tissue structural remodelling.

Immunohistochemicalanalysis combined with fibronectin and tenascin enables the diagnosisof the type of fibroproliferative lung diseases to be carried out withgreater reliability. For example, the detection of tenascin indicatesthe lesion is at an active stage and that the response to treatment ofthe condition could be more effective than if it were not present, thusindicating chronification. This knowledge is important in terms ofprognosis and therapy given that, with functional lung pathology,diagnosis - usually based on small tissue samples - is sometimescomplicated. This is because we as pathologists see alterations inshape and structure, changes that have to be complemented withradiological findings and clinical history. Thus, the protocolising oftechniques that enable the carrying out of histopathological diagnoseswith enhanced reliability is eminently positive.