[Humoral and cellular inflammatory mediators in acute lung injury: friends or enemies? ]. / Mediatori infiammatori umorali e cellulari dell'Acute Lung Injury: amici o nemici?

ABSTRACT

Diffuse lung injury (DLI) is characterised by damage to the alveolar and endothelial epithelium that leads to acute respiratory insufficiency. From the histological point of view, this pathological process proceeds through an initial exudative phase which is followed by the organisation of the inflammatory infiltrate up to the deposit of collagen and fibrin which seriously compromises gaseous exchanges. The clinical expression typical of this pathology consists of Acute Lung Injury/Acute Respiratory Distress Syndrome (ALI/ARDS) characterised by hypoxemia resistant to oxygen therapy, tachypnea and the presence of bilateral infiltrates on conventional X-ray of the thorax. Although the etiology is multifactorial, the pathogenesis depends on the uncontrolled activation of the inflammation system in its humoral and cellular components. The present paper examines the principal studies regarding the most important mediators. From an analysis of the literature it emerges that some cytokines (IL-1betha, IL-6, IL-6ra) and cellular mediators (NF-kB, sFasL) are responsible for the epithelial damage by way of complex mechanisms that include apoptosis. Studies carried out up to the present have not however evidenced any independent pathway decisive for pathogenesis. This shows that inflammation is in effect a multiform process that originates precisely as a result of the mutual interaction of the factors implicated in it. The humoral and cell mediators can, however, be used as clinical indicators correlatable with the clinical and physiopathological outcome.