Proliferation of type II pneumocytes and alteration in their apical surface membrane antigenicity in pulmonary sarcoidosis

Immunohistochemical evaluation of surfactant proteins and lymphocyte phenotypes in the lungs of cattle with natural tuberculosis

The aim of the present study was to evaluate the immunohistochemical expression of pulmonary surfactant proteins (SP-A, SP-B, SP-C) and lymphocytic phenotypes in the lungs of 12 cattle with natural tuberculosis. Grossly, the disease-affected cattle revealed numerous granulomas in the lung lobes. Histopathological examination found multiple lung granulomas with typical cellular elements. Type II pneumocytes with adenomatous proliferation around the granulomas were strongly immunopositive for SP-A and SP-B compared to normal type II cells. Clara cells showed also cytoplasmic immunopositivity for these surfactant proteins. Positive immunolabelling for proSP-C was detected exclusively in the normal and proliferative type II pneumocytes, and the reaction was marked in the perinuclear area of the cells. CD3(+) T and CD79αcy(+) B lymphocytes were predominantly localized in the fibrotic capsule margin of advanced granulomas, in greater numbers than in the early granulomas. In conclusion, the study found that type II pneumocytes proliferated highly and surrounded the tuberculous granulomas in the lungs, that hyperplastic type II pneumocytes synthesized and secreted larger amounts of surfactant proteins than the normal type II cells, and that SP-A might have played an important role in host defence against the mycobacterial agents. Additionally, the presence of high numbers of CD3(+) T cells throughout the granulomas confirmed the dominance of a cellular immune response in cattle tuberculosis.

Heterogeneous proliferation of type II pneumocytes in usual interstitial pneumonia

AIMS

Heterogeneous alveolar fibrosis, the most specific pathological finding in idiopathic pulmonary fibrosis (IPF)/usual interstitial pneumonia (UIP), enables differentiation of UIP from other interstitial pneumonias. Heterogeneous and mild alveolar injury may occur, and this will be a clue to clarifying the pathogenesis of UIP.

METHODS

We examined nine lung biopsy specimens obtained from patients with IPF and five control specimens. We semi-quantitatively examined alveolar injury by measuring the density of type II pneumocytes. Serial 3 microm sections were stained with anti-Thomsen-Friedenreich (TF) antibody. We divided each UIP lesion into three areas: area near fibrosis (fibrous area), area with an apparently normal alveolar structure (normal area), and area between the fibrous and normal areas (intervening area).

RESULTS

Immunostaining with anti-TF antibody stained the apical surface of type II pneumocytes and enabled us to recognise and count type II pneumocytes. The density of type II pneumocytes was increased in the fibrous area, and gradually decreased away from the fibrous lesion. The densities of type II pneumocytes in the above three areas were, respectively: 13.9+/-2.0, 7.2+/-1.6, and 9.5+/-1.6/mm alveolar length. The densities in the fibrous and intervening areas were significantly greater than those in the normal area and in control specimens (6.6+/-0.7/mm).

CONCLUSIONS

If the density of type II pneumocytes indicates their degree of regeneration after alveolar injury, it reflects the severity of the pre-existing injury. This study confirms that heterogeneous and mild alveolar injury occurs in UIP.

Proliferation of type II pneumocytes in the lung biopsy specimens reflecting alveolar damage

Proliferation of type II pneumocytes may be the most sensitive pathological indicator of alveolitis, and the density of type II pneumocytes reflecting the severity of the recent alveolar damage. Twenty-nine patients were divided into three groups by the severity of ground-glass opacities on the CT scans; the severe (acute), the moderate (subacute) and the mild (chronic) groups. We compared the density of type II pneumocytes in the transbronchial lung biopsy specimens and cell analysis of bronchoalveolar lavage (BAL) fluid with the ground-glass opacities. Clinical and laboratory findings and BAL fluid analysis also corresponded well with this grouping. Type II pneumocytes were selectively stained with an antibody against Thomsen-Friedenreich and the density of the type II pneumocytes was expressed as the number per 1 mm alveolar septal length. The densities of the type II pneumocytes in the severe, the moderate, the mild, and the control groups were 21.2+/-1.1, 14.4+/-7.2, 11.0+/-3.3 and 7.5+/-0.9/mm, respectively. There were significant differences between the acute group and the other three groups, and between the control and chronic groups. The density of type II pneumocytes is a useful index for evaluating alveolar damage even in mild alveolitis.

Glycocalyx of lung epithelial cells

Due to their diversity and external location on cell membranes, glycans, as glycocalyx components, are key elements in eukaryotic cell, tissue, and organ homeostasis. Although information on the lung glycocalyx is scarce, this article aims to review, discuss, and summarize what is known about bronchoalveolar glycocalyx composition, mainly the sialic acids. It was deemed relevant, however, to make a brief introductory overview of the cell glycocalyx and its particular development in epithelial cells. After that, follows a summary of the evolution of the knowledge regarding the bronchoalveolar glycocalyx composition throughout the years, particularly its morphological features. Since sialic acids are located terminally on the bronchoalveolar lining cells' glycocalyx and play crucial roles, we focused mainly on the existing lung histochemical and biochemical data of these sugar residues, as well as their evolution throughout lung development. The functions of the lung glycocalyx sialic acids are discussed and interpretations of their roles analyzed, including those related to the negative overall superficial shield provided by these molecules. The increasing presence of these sugar residues throughout postnatal lung development should be regarded as pivotal in the development and maintenance of a dynamic bronchoalveolar architecture, supporting the normal histophysiology of the respiratory system. The case for a profound knowledge of lung glycocalyx--given its potential to provide answers to serious clinical problems--is made with particular reference to cystic fibrosis. Finally, concluding remarks and perspectives for future research in this field are put forth.

Pathological features of the lung in fatal high altitude pulmonary edema occurring at moderate altitude in Japan

In order to characterize the pathological features of high altitude pulmonary edema (HAPE) occurring at moderate altitude in Japan, we performed routine hematoxylin and eosin (HE) staining in lung materials from HAPE autopsied cases. We also undertook advanced immunohistochemical staining for observation of type II pneumocytes, pulmonary surfactant (PS), and mast cells in the lung of HAPE cases to examine the biological changes within the lung parenchyma. The pathological findings of HAPE were characterized by alveolar edema, congestion of pulmonary vessels, alveolar hyaline membranes, alveolar hemorrhage, and multithrombi and fibrin clots, but maintained alveolar structure. The immunostaining results showed that the type II pneumocytes were cellular fusion, deformity, and exfoliation from the walls of alveoli; the PS not only lined the alveolar surface, but was also patchily distributed within alveoli; and the number of mast cells were increased (9.0 +/- 0.9 cells/mm(2)) compared to that in controls (1.1 +/- 0.4 cells/mm(2)) (p < 0.01). We conclude that the pathological features of HAPE at moderate altitude in Japan are similar to others reported worldwide, and that the type II pneumocytes, PS, and mast cells may contribute to some extent to pathophysiological parts in the development and progression of HAPE.