Circulating levels of the long pentraxin PTX3, an acute phase mediator of innate immunity, in acute lung injury/acute respiratory distress syndrome: functional and prognostic correlations

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is characterized by an important inflammatory reaction involving both lungs, often spreading systemically. Pentraxin 3 (PTX3) has recently been described as a mediator of the acute phase of innate immunity. It belongs, together with C-reactive protein (CRP), to the pentraxin superfamily. PTX3 is produced by endothelial cells, fibroblasts, mononuclear phagocytes and dendritic cells in response to primary inflammatory signals (IL-1, tumor necrosis factor, LPS). Its involvement in the pathogenesis of ALI/ARDS seems probable and potentially interesting for the pathophysiology, the diagnosis and possibly the therapy of the syndrome. We measured PTX3 levels, by an ELISA test, in the sera of 25 patients affected by ALI/ARDS. We also collected data related to etiology, pulmonary mechanics, gas exchange, systemic inflammatory involvement, microbiology, blood cells and the outcome of these patients. PTX3 was markedly elevated in all 25 patients (average 111.07 ± 192.01 ng/ml; range 4.94–922.91 ng/ml). In no patient were PTX3 levels lower or equal to the physiological threshold of 2 ng/ml. Levels of logPTX3 were significantly different between survivor and nonsurvivor patients (1.465 ± 0.529 log ng/ml vs 1.950 ± 0.643 log ng/ml; P = 0.05). Patients with two or more organ failures (besides the lung) also had logPTX3 levels significantly higher than patients with just one additional organ failure (1.936 ± 0.597 log ng/ml vs 1.423 ± 0.542 log ng/ml; P < 0.04). The same was true when PTX3 levels in patients with septic shock were compared with PTX3 levels in patients without shock (262.465 ± 350.727 ng/ml vs 63.257 ± 70.261 ng/ml; P < 0.03). PTX3 and logPTX3 were correlated with body temperature (r = 0.56 P < 0.01; r = 0.51 P = 0.01) and with arterial blood pH (r = -0.53 P < 0.01; r = -0.53 P < 0.01). We have underlined a relationship between circulating levels of PTX3 and some markers of the severity of systemic involvement. PTX3 could be an indicator of the gravity of the systemic inflammatory reaction and of unfavourable outcome in ALI/ARDS patients.