Idiopathic pulmonary fibrosis/cryptogenic fibrosing alveolitis

Abstract. Idiopathic pulmonary fibrosis (IPF), synonymous with cryptogenic fibrosing alveolitis (CFA), is a progressive and usually fatal disease of unknown cause characterized by sequential acute lung injury with subsequent scarring and end-stage lung disease. Historically, IPF/CFA encompassed a heterogeneous group of different histological and clinical entities arising in an idiopathic setting. Recently, the American Thoracic Society (ATS) and European Respiratory Society (ERS) core committee has redefined diagnostic criteria for both IPF/CFAand idiopathic interstitial pneumonias confining the term IPF/CFA to patients with a histological pattern of usual interstitial pneumonia on lung biopsy. This review attempts to refine the clinico-radiological-pathological features that together define IPF/CFA as it is understood today, and to summarize the rationale of new therapeutic approaches based on the current understanding of the pathogenetic mechanisms.     

Tenascin immunoreactivity in cryptogenic fibrosing alveolitis

Tenascin is a hexameric extracellular matrix (ECM) glycoprotein which has been demonstrated to have a temporal relationship with active scar formation in adult tissues. We hypothesized that this ECM protein might therefore serve to identify areas of active scarring in lung biopsies from patients with cryptogenic fibrosing alveolitis (CFA). The distribution of tenascin was examined in open lung biopsies from ten patients with CFA, six patients with sarcoidosis, and six pulmonary resection specimens from patients with no evidence of interstitial lung disease, using an immunohistochemical technique. Immunoreactive tenascin was not identified in histologically normal control lung parenchyma and was only focally found around large aggregates of granulomas in sarcoidosis. In the CFA, tenascin production was demonstrated in minimally damaged alveolar walls and areas of active disease but not in end-stage scarred lung. There was considerable local heterogeneity of staining within cases, which did not appear to relate to the density of the local inflammatory infiltrate. Large plaques of tenascin were noted to be particularly associated with hyperplastic type II alveolar epithelial lining cells, which are recognized to produce fibrogenic cytokines. The examination of tenascin expression in open lung biopsies from patients with CFA may be useful in assessing fibrogenic activity and may thus provide additional prognostic information.     

Bronchoalveolar macrophages in sarcoidosis and cryptogenic fibrosing alveolitis

Previous reports suggest that blood monocytes and tissue epithelioid cells in patients with sarcoidosis are‘activated’, but few studies have been undertaken on human alveolar macrophages. In the present study, bronchoulveolar lavage samples have been obtained from eighteen patients with sarcoidosis and these have been compared with twenty controls and twenty-nine patients with non-granulomatous chronic inflammatory interstitial lung disease (cryptogenic fibrosing alveolitis). Assessment of the functional state of the macrophages was made by measurements of C3b receptor sites on the cell membrane, intra and extracellular lysosomal enzyme (β-D-glucosaminidase) and the degree of spreading of macrophages on glass. C3b receptor sites and intracellular levels of lysosomal enzyme were significantly reduced in sarcoidosis compared to controls; levels of extracellular enzyme in the lavage supernatant fluid and macrophage spreading were similar to controls. These features suggest that alveolar macrophages from patients with sarcoidosis are not “activated”. By contrast, in cryptogenic fibrosing alveolitis. macrophages show a greater extracellular intracellular ratio of lysosomal enzyme and more spreading, suggestive of ‘activation’.     

Bronchiolar-alveolar cancer in idiopathic fibrosing alveolitis

An observation of bronchiolo-alveolar carcinoma that developed in the presence of the idiopathic fibrosing alveolitis (IFA) in a woman of 57, is described. The duration of IFA was 12 years. Diffuse pneumosclerosis with the development of the so-called "honey-comb" lungs was observed. Numerous confluent foci of the bronchiolo-alveolar carcinoma in both the lungs are found in the presence of alterations typical for IFA (diffuse sclerosis of alveolar septa, microcystosis). The cause of death was progressing respiratory deficiency.     

Recent advances in the aetiology of cryptogenic fibrosing alveolitis

Crytogenic fibrosing alveolitis is the commonest intersititial lung disease but, until recently, very little has been known about its aetiology. The histopathologist usually sees this disease at transbronchial biopsy or at autopsy. This article reviews the current knowledge of the aetiology of cryptogenic fibrosing alveolitis looking at possible infective, occupational, drug-related, smoking-associated, genetic and dietary factors. Knowledge of the possible roles of these factors in the disease process informs histopathologists when they are reporting these biopsies and enables them to make a larger contribution to defining the pathogenetic mechanisms.     

Desquamative form of cryptogenic fibrosing alveolitis in a cat

Bronchopulmonary disease is not uncommon in cats, many cases falling into the categories of chronic bronchitis and the "feline asthma syndrome". We report a case of chronic bronchopulmonary disease in an adult cat, which was initially diagnosed as chronic bronchitis. Failure to respond to appropriate therapy led to euthanasia. At necropsy, the lungs exhibited multifocal areas of consolidation, especially at the periphery of the diaphragmatic lobes. Histopathological examination revealed a striking variability of lesions, with interstitial fibrosis and intra-alveolar accumulations of macrophages in addition to alveolar epithelialization and smooth muscle hyperplasia. These changes were consistent with those described for the desquamative form of cryptogenic fibrosing alveolitis in human beings.     

Fine structural changes in cryptogenic fibrosing alveolitis and asbestosis

Lung biopsies from 17 patients with cryptogenic fibrosing alveolitis of a cellular rather than fibrotic pattern were examined by transmission electron microscopy in the hope that such cases would show features of pathogenetic significance. Further selection was made by choosing minimally affected areas. There was no ultrastructural evidence of immune complex deposition but alveolar epithelial and capillary damage was frequently found (17 and 14 of the 17 cases respectively). Alveolar epithelial injury consisted of patchy necrosis and regenerative hyperplasia. Alveolar capillary injury consisted of cytoplasmic swelling and basement membrane thickening and reduplication. Many of these features have not been emphasized in previous reports and their prominence in early stages of the disease suggest that they may have pathogenetic significance, possible mechanisms of which are discussed. Similar findings identified during the course of this study in 8 asbestos workers suggest that similar pathogenetic mechanisms may operate in asbestosis.     

Circulating immune complexes in patients with cryptogenic fibrosing alveolitis.

Increased Clq binding levels have been obtained in serum from twenty-one (50%) of forty-two patients with cryptogenic fibrosing alveolitis (CFA) suggesting the presence of circulating immune complexes. There was a low frequency of positive results using a number of other tests for circulating immune complexes. The increased Clq binding levels were observed in six (35%) out of seventeen patients with lone lung involvement and in fifteen (60%) out of twenty-five patients with extrapulmonary connective tissue disorders. There was an especially close correlation between arthritis and elevated Clq binding. A strong correlation between Clq binding levels and levels of circulating rheumatoid factor (RF) and IgG, and enhancement in macrophage radiobioassay tests using RF-containing sera, suggested that RF might be involved in the circulating immune complexes in these patients. DNAase pre-treatment of sera did not influence the findings, and there was no correlation between Clq binding and levels of immunofluorescent ANA, C-reactive protein levels, or platelet counts. A weak correlation between Clq binding and erythrocyte sedimentation rates, and slightly lower binding levels in treated than untreated patients with 'lone' CFA suggested that binding levels may give some indication of disease activity and may in some instances be influenced by treatment.     

Expression of tumour necrosis factor-α in cryptogenic fibrosing alveolitis

We have studied 15 cases of cryptogenic fibrosing alveolitis stained with a monoclonal antibody reactive with human tumour necrosis factor-α (TNFα), a cytokine that has been implicated in inflammation and fibrosis. Seven were examples of lone cryptogenic fibrosing alveolitis and eight were examples of cryptogenic fibrosing alveolitis in patients with systemic sclerosis. There was widespread staining of epithelial cells, particularly hyperplastic type II pneumocytes. Macrophages stained only weakly. In a control group of 10 patients dying of unrelated conditions, staining for TNFα was weak and, in the alveolar epithelium, was confined to a very occasional type II pneumocyte. The strong expression of TNFα in hyperplastic type II pneumocytes suggests that TNFα produced during alveolar epithelial regeneration may play a part in the fibrosis seen in this disease.     

A type 2 (Th2-like) pattern of immune response predominates in the pulmonary interstitium of patients with cryptogenic fibrosing alveolitis (CFA).

CFA is an inflammatory condition of the lungs resulting in scarring, pulmonary failure and death. The etiology of the disease is unknown, but the pathogenesis is believed to involve a persistent immunological reaction to unidentified antigen in the lung resulting in tissue damage. Recent advances in our understanding of the immune system have shown that different patterns of stimulatory cytokines are produced at sites of inflammation by a range of cell types. Patterns of cytokine reproduction by inflammatory cells are recognized to be associated with different patterns of immunological response, and these have been described as type 1 (or Th1-like) and type 2 (or Th2-like) on this basis. We have studied cytokine expression in the intestinal inflammatory cell infiltrate in lung tissue from patients with CFA using mRNA in situ hybridization and immunohistochemistry. Our results show that while there is evidence for both a type 1 (characterized by interferon-gamma (IFN-gamma) and type 2 (characterized by IL-4 and IL-5) response present in CFA, the type 2 (or Th2) pattern of cytokines appears to predominate. This would be consistent with a possible role for the humoral immune response in the pathogenesis of this condition. In addition, recent evidence suggests that IL-4 and IFN-gamma may be important regulatory factors for pulmonary fibroblasts. The relative paucity of IFN-gamma may contribute to the excessive fibroblast activation, deposition of collagen and scar formation that occurs in CFA.     

Characterization of human lymphoid cell-mediated antibody-dependent cytotoxicity (LDAC)

Cytotoxicity was studied in a model system using chicken erythrocytes (Ch RBC) labelled with ⁵¹Cr as target cells and human peripheral blood lymphoid cells as effector cells. In vitro human lymphoid cells are highly efficient in destroying target cells coated with anti-target cell antibody, the mean net percentage cytotoxicity of lymphoid cells from fifty-eight control subjects being 64·27±2·06 (SEM). In the absence of antibody the mean net percentage cytotoxicity was 6·90±0·46. As little as 10 ng rabbit anti-Ch RBC IgG was required to cause significant target cell lysis. Studies on the nature of the lymphoid cell-dependent cytotoxic antibody showed that it is localized in the 7S IgG region of whole serum and that an intact Fc region is required; the F(ab')₂ fragment obtained by pepsin digestion of IgG was inactive although able to inhibit the cytotoxic activity of the whole undigested IgG. Investigation of the kinetics of LDAC showed that when antibody was added to the final culture medium target cell lysis progressed rapidly (detectable within 2 hr) and linearly with time up to 8 hr. Thereafter the rate of lysis decreased reaching a maximum after 12 hr culture. With cultures containing target cells which have been pre-incubated with antibody, lysis occurred even more rapidly, detectable within 30 min and reaching a maximum after only 3–4 hr culture. The maximum cytotoxicity in this system was, however, lower than that obtained when antibody was added directly to the culture medium. Cytotoxicity could be inhibited by the addition of aggregated human IgG, as little as 5 μg causing 100% inhibition of target cell lysis. Study of the nature of the effector lymphoid cell showed, first, that viable cells were required, twice frozen/thawed lymphoid cell suspensions being inactive; secondly, that active protein synthesis by the effector cell was not an essential prerequisite, pretreatment of lymphoid cells with mitomycin C having no significan effect on their ability to lyse antibody-coated target cells but significantly reducing their ability to transform in response to the mitogen PHA; thirdly, that the effector cell is non-phagocytic, non-plastic or glass-adherent and does not bear surface immunoglobulin; and fourthly that significant cytotoxicity is detectable even with a total lymphoid cell to target cell ratio of 1:2.     

Influence of human T lymphotrophic virus type I on cryptogenic fibrosing alveolitis - HTLV-I associated fibrosing alveolitis: proposal of a new clinical entity

Human T lymphotrophic virus type-I (HTLV-I), a human retrovirus, infects CD4+ lymphocytes and is thought to modify their function; a possible association with pulmonary diseases has also been suggested. However, little is known about the influence of HTLV-I on cryptogenic fibrosing alveolitis (CFA), a chronic inflammatory interstitial lung disease of unknown aetiology. In order to clarify the influence of HTLV-I infection on CFA, 72 CFA patients with and without HTLV-I infection were examined. HTLV-I positive CFA patients were likely to have larger affected areas and to show traction bronchiectasis with honeycombing change. An imbalance of matrix metalloproteinases and tissue inhibitor of metalloproteinases were also observed in the BALF of HTLV-I positive CFA patients. CD3+/CD25+ lymphocyte percentage was significantly higher in the BALF of HTLV-I positive patients compared to negative patients. MIP-1alpha, IP-10 and sICAM levels in BALF were also significantly higher in HTLV-I positive patients than in negative patients. The levels of MCP-1 and IL-8 were not significantly different. In HTLV-I positive patients, the MIP-1alpha and IP-10 levels showed a significant positive correlation with percentage of CD3+/CD25 lymphocytes. HTLV-I positive CFA patients showed a larger lesion than negative patients and exhibited increased levels of certain cytokines that correlated with activated T cells in the BALF. We suggest that HTLV-I infection may contribute to the development of CFA via activation of T cells. We also propose that these features should be taken into consideration in the treatment of CFA in HTLV-I infected individuals.     

Reduced antibody-dependent cell-mediated cytotoxicity in systemic lupus erythematosus.

The peripheral blood mononuclear cells from twenty-three patients with SLE were studied. They showed a reduction in antibody-dependent cell-mediated cytotoxicity. This reduction was significantly related to disease activity. No correlations were found with other clinical features. Some of the possible explanations for this finding are discussed.     

Antibody reactive in antibody-dependent cell-mediated cytotoxicity following influenza virus vaccination

The antibody reactive in antibody-dependent, cell-mediated cytotoxicity (ADCC) to influenza virus-infected cells was measured in two groups of seven volunteers each, before and after immunization with inactivated or live attenuated A/Victoria/3/75 influenza virus vaccines. Age-matched controls were seven adult individuals who experienced natural influenza infection due to A/Victoria/3/75-like virus strain. After inactivated whole influenza virus immunization all the subjects showed a significant rise of the antibody reactive in ADCC (from a mean value of 4.7% to 17.1% cytotoxicity, before and 5 weeks after immunization, respectively) as well as of hemagglutination inhibition (HI) antibody (fourfold or greater increase). These immune responses were similar to those observed among naturally infected controls. After live attenuated virus vaccination, no significant increase in titer of antibody reactive in ADCC was detected, even though the vaccine induced significant increase of HI antibody titer. Little correlation was found between ADCC and HI antibody rises in sera of recipients of inactivated virus vaccine and of naturally infected individuals, while, in live attenuated influenza virus vaccinees, the rise of HI antibody titer did not correspond to a significant increase of ADCC antibody titer; several subjects who developed a significant rise in ADCC antibody titer did not show significant variation in antibody to neuraminidase and/or to complement fixation influenza virus antigens.     

Measurement of antibody-dependent cell-mediated cytotoxicity by Hb-enzyme release assay (Hb-ERA)

A non-isotope method, hemoglobin-enzyme release assay (Hb-ERA), for measuring antibody-dependent cell-mediated cytotoxicity (ADCC) has been successfully developed. The assay is based on the fact that hemoglobin has peroxidase activity capable of catalyzing the oxidation of o-phenylenediamine to give coloration which can be measured by spectrophotometer. In comparison to the conventional 51Cr release assay, Hb-ERA is economic, sensitive, reproducible and does not have the shortcomings associated with manipulation of radioactive substances. It is applicable in clinical and research laboratories of any scale. The optimum conditions for the assay are as follows: an effector cell: target cell ratio of 10:1 and an incubation period of 14-16 h at 37 degrees C in 5% CO2. The splenic ADCC activity of mice was measured. The cytotoxic index of mice aged 10-14 weeks (39.71 +/- 11.19) was significantly higher than that of 20-24 week-old mice (18.42 +/- 10.31) (P less than 0.001). The ADCC activity is not influenced by sex. The merits and drawbacks of Hb-ERA are objectively evaluated.     

Serum antibodies and their role in antibody-dependent cell-mediated cytotoxicity in aspergillosis

A total of 22 sera from patients with aspergilloma and allergic bronchopulmonary aspergillosis (ABPA) were examined concomitantly for specific antibody against Aspergillus fumigatus antigen and for their activity in antibody-dependent cell-mediated cytotoxicity (ADCC) against Aspergillus antigen-coated target cells. These sera demonstrated significant precipitin bands in agar gel double diffusion test (78% of ABPA and 75% of aspergilloma sera), while in indirect immunofluorescence studies all sera showed positive reactivity with a titer distribution of 1:40 to 1:160 and 1:40 to 1:320, respectively, for ABPA and aspergilloma sera. In enzyme-linked immunosorbent assay all sera demonstrated titers varying from 1:200 to 1:6400. Several sera also displayed marked cytotoxic reactions against A. fumigatus antigen-coated SB target cells in ADCC assays using normal lymphocytes as effector cells (35% of aspergilloma and 25% of ABPA sera). These findings suggest a role for ADCC activity in patients with Aspergillus infections.     

Morphofunctional characteristics of pulmonary and bronchial arteries in bronchial asthma, chronic obstructive lung disease, idiopathic fibrosing alveolitis

Morphological and morphometric studies have shown that secondary pulmonary hypertension is characterized by more pronounced pathological changes in the pulmonary arterial branches in severe chronic obstructive lung disease (COLD) than in idiopathic fibrosing alveolitis. Secondary pulmonary hypertension does develop in atopic bronchial asthma. Moreover, there are more significant pathological changes in the pulmonary arteries than in the bronchial ones. In severe COLD, the development of emphysema affects that of pulmonary arterial hypertension.     

Variation in expression of antibody-dependent cell-mediated cytotoxicity in rodents with malaria.

Antibody-dependent cell-mediated cytotoxicity (ADCC) against mouse erythrocytes sensitized with immunoglobulin G was studied in mice with malaria. Spleen cells from mice had enhanced cytotoxic activity early in Plasmodium berghei infection but not later in the disease. Sera from infected animals and partially purified malarial immune complexes inhibited ADCC. In addition, ADCC was diminished in spleen cells from mice infected with the lethal variant of P. yoelii 17x compared with that in mice infected with the nonlethal variant. P. berghei-infected erythrocytes did not release 51Cr when incubated with effector cells unless the erythrocytes were sensitized with antibodies against normal mouse erythrocytes.     

Decreased antibody-dependent and spontaneous cell-mediated cytotoxicity in patients with chronic renal failure

Antibody-dependent and spontaneous lymphocytotoxicity of blood mononuclear cells from 15 patients with chronic renal failure was studied in allogeneic K-562 and xenogeneic chicken erythrocyte test systems. Both antibody-dependent and spontaneous cytotoxic activities were significantly decreased in uremic patients as compared to the corresponding mean values of healthy control persons and non-uremic patients with the same underlying diseases. The addition of autologous serum further reduced the impaired cytotoxic capacity of uremic lymphocytes. Uremic sera also inhibited the antibody-dependent and spontaneous lymphocytotoxicity of healthy individuals.