Idiopathic Fibrosing Alveolitis: A Review of Information

Interstitial lung diseases are a large group of diseases of various etiologies characterized by inflammatory lesions of the walls of the alveoli (alveolitis) and surrounding interstitial tissue. Currently, this group includes more than 130 diseases; but interstitial lung diseases are not attributed to infectious lung diseases of known etiology and malignant tumors (eg, lymphogenous carcinomatosis), in which a similar clinical symptomatology may appear.

Depending on the etiology, interstitial lung diseases are distinguished between known and unknown etiology, and within each group two subgroups are distinguished (the presence or absence of granulomas in the interstitial tissue).

BM Korenev, EA Kogan, and EN Popova (1996) propose to classify interstitial lung diseases, taking into account the morphological features of pulmonary interstitial lesions. Interstitial lung diseases have a number of common characteristics:

• progressive clinical course;
• increasing respiratory insufficiency of restrictive type;
• X-ray picture of diffuse lesion of pulmonary tissue in the form of amplification and deformation of the pulmonary pattern and small- or medium-focus dissemination;
• the leading role of immune mechanisms in the pathogenesis of most nosological forms.

Idiopathic fibrosing alveolitis is a disseminated lung disease characterized by inflammation and fibrosis of pulmonary interstitium and airborne spaces by disorganization of the structural and functional units of the parenchyma leading to the development of restrictive changes in the lungs, disruption of gas exchange, and progressive respiratory failure.

The disease was first described by Hamman and Rich in 1935.

Causes and pathogenesis of idiopathic fibrosing alveolitis

The causes of idiopathic fibrosing alveolitis have not been fully established. The following possible etiological factors are currently being discussed:

• virus infection - the so-called latent, "slow" viruses, primarily the hepatitis C virus and the human immunodeficiency virus. The possible role of adenoviruses, the Epstein-Barr virus (Egan, 1995) is also assumed. There is a point of view about the dual role of viruses in the development of idiopathic fibrosing alveolitis - viruses are the primary triggers of the development of damage to lung tissue and, in addition, the virus replicates in the already damaged tissue, which naturally contributes to the progression of the disease. It is also established that the viruses interact with the genes that regulate cell growth, and thus stimulate collagen production, fibro-oocyte formation. Viruses can also increase the already existing chronic inflammation;
• ecological and professional factors - there are data on the relationship of idiopathic fibrosing alveolitis with prolonged professional contact with metal and wood dust, brass, lead, steel, some types of inorganic dust - asbestos, silicate. The etiological role of aggressive etiological factors is not ruled out. However, it should be emphasized that these occupational factors cause pneumoconiosis, and, with reference to idiopathic fibrosing alveolitis, can probably be considered as triggering factors;

Idiopathic fibrosing alveolitis - Causes and pathogenesis

Symptoms of idiopathic fibrosing alveolitis

Idiopathic fibrosing alveolitis develops most often between the ages of 40 and 70, with men 1.7-1.9 times more likely than women.

The most typical is a gradual, subtle start, but in 20% of patients the disease begins acutely with an increase in body temperature and pronounced dyspnea, but later the body temperature becomes normal or becomes subfebrile.

For idiopathic fibrosing alveolitis, the complaints of patients are extremely typical, and a careful analysis of which allows one to suspect this disease:

• shortness of breath is the main and permanent manifestation of the disease. At first, shortness of breath is less pronounced, but as the disease progresses, it grows and becomes so pronounced that the patient can not walk, serve himself, and even talk. The more severe and prolonged the disease, the more pronounced dyspnea. Patients note the constant nature of dyspnea, the absence of attacks of suffocation, but often emphasize the inability to take a deep breath. Because of progressive dyspnoea, patients gradually decrease their activity and prefer a passive lifestyle;

Idiopathic fibrosing alveolitis - Symptoms

Diagnosis of idiopathic fibrosing alveolitis

An important marker of the activity of idiopathic fibrosing alveolitis is an increase in serum level of glycoproteins of surfaganga A and D, which is caused by a sharp increase in the permeability of the alveolar-capillary membrane.

With the development of decompensated pulmonary heart, a moderate increase in the content of bilirubin, alanine aminotransferase, gamma-glutamyl transpeptidase in the blood is possible.

Immunological analysis of blood is characterized by a decrease in the number of T-lymphocytes-suppressors and an increase in T-helpers, an increase in the overall level of immunoglobulins and cryoglobulins, increased titres of rheumatoid and antinuclear factors, and the appearance of anti-pulmonary antibodies, circulating immune complexes. These changes reflect the intensity of autoimmune processes and inflammation of the interstitium of the lungs.

Idiopathic fibrosing alveolitis - Diagnosis

[1], [2], [3], [4]