Portal de Periódicos da CAPES

XV. Pneumocystosis pathophysiology

1998; Oxford University Press; Volume: 22; Issue: 1-2 Linguagem: Inglês

10.1111/j.1574-695x.1998.tb01196.x

1574-695X

Marie-Claude Prévost, R. Escamilla, El Moukhtar Aliouat, Nicolas Ceré, Pierre Coudert, Eduardo Dei‐Cas,

Blood disorders and treatments

Although immunodeficiency represents the main etiopathogenetic factor [1], the basic mechanism of Pneumocystis carinii pneumonia (PCP) pathogenesis remains poorly understood. When growing into alveoli, P. carinii interacts with cells and other components; the initial stages of PCP involve parasite attachment to alveolar epithelium, preferentially to type I pneumocytes [2–5], and produce an increase in alveolo-capillary permeability [5, 6]; this last event leads to an influx of plasma proteins into the alveolar space and thereby may alter the composition of epithelial alveolar lining fluid. Pulmonary surfactant, which covers the alveolar surface, plays an important role in the homeostasis of the alveolar environment and in the defense of the lung [7–11]. Since P. carinii comes into close contact with surfactant, it seems logical to suppose, on the one hand, that the parasite could interact with surfactant components and, on the other hand, that pulmonary surfactant may have an impact on the pathophysiology of PCP. Pulmonary surfactant, which is synthesized by alveolar type II cells, is a complex material containing lipids and proteins (Table 1) [7, 8]. Its synthesis is developmentally regulated in fetal lung and can be accelerated by glucocorticoids and other hormones [12]. Lipids are the main components (90%) of pulmonary surfactant [7, 8]. Phospholipids represent 80–90% of the lipids and phosphatidylcholines, which are mainly dipalmitoylphosphatidylcholines, constitute the major part (70–80%) of phospholipids. Cholesterol comprises the largest amount of neutral lipids. In addition to lipids, four surfactant-specific proteins (SP) with different structural properties have been identified [13, 14]: SP-B and SP-C, which represent only 1% of total surfactant, are two extremely hydrophobic proteins; they are involved in keeping surface active properties of the surfactant [14, 15]. SP-A and SP-D are hydrophilic proteins; SP-A …