[Molecular bases for the development of variants of idiopathic fibrosing alveolitis]

The purpose of the study was to examine the specific features of morphological manifestations and molecular mechanisms of controlling the processes of proliferation, apoptosis, cell differentiation, neoangiogenesis, and fibrosis, which result in lung tissue rearrangement in different types of idiopathic fibrosing alveolitis (IFA). Open and transbronchial biopsy specimens obtained from 103 patients with IFA and intact lung tissue biopsy specimens taken from those clinically diagnosed as having sarcoidosis as a control group were examined. The serial paraffin sections immunohistochemically revealed the following antigens: cytokeratins 5, 6, 7, 8, 19 (Uni-Heidelberg, DAKO), MMP 1, MMP 2, MMP 7, and TIMP 4, Apo-protein (Novocastra), Ki67, PCNA, PDGF, EGFR, CD34, SMA (smooth muscle actin), FGFb (LabVision). Biotin-conjugated antibodies to murine and rabbit immunoglobulins (Dako LSAB + KIT, PEROXIDASE) were used as secondary antibodies. The nuclei were stained with hematoxylin. Positive and negative control tests were carried out. The results of immunohistochemical tests were estimated in percentage of cells showing positive reactions (Ki67, PCNA), as well as those of a semiquantitative analysis in scores and statistical analyses (Mann-Whitney U-test, Fisher's test, and Spearman's rank correlation coefficient) were employed. OIP was ascertained to differ from other IFA in higher values of the cytokines under study, as well as in the predominant rearrangement of the lung interstice and dysregeratory epithelial changes at the site of respiratory bronchiolar transformation. At the same time there was an intensive proliferation of the epithelium and stromal cells (high expression of PCNA, PDGF by hyperplastic alveolocytes, alveolar macrophages, fibroblasts and myofibroblasts), and neogenesis (the high density of newly formed vessels with endothelial expression of CD34). Elevated alveolocytic apoptosis (from Apo-protein expression) was also observed. Cell proliferation and neoangiogenesis was attained by high MMPs expression. The practical value of the study is that the expression of the study markers may serve as a criterion for differential diagnosis and determination of prognosis in different types of IFA.