Effect of Corticosteroid on Lung Parenchyma Remodeling at an Early Phase of Acute Lung Injury

Abstract

In vivo (lung resistive and viscoelastic pressures and static elastance) and in vitro (tissue resistance, elastance, and hysteresivity) respiratory mechanics were analyzed 1 and 30 days after saline (control) or paraquat (P [10 and 25 mg/kg intraperitoneally]) injection in rats. Additionally, P10 and P25 were treated with methylprednisolone (2 mg/kg intravenously) at 1 or 6 hours after acute lung injury (ALI) induction. Collagen and elastic fibers were quantified. Lung resistive and viscoelastic pressures and static elastance were higher in P10 and P25 than in the control. Tissue elastance and resistance augmented from control to P10 (1 and 30 days) and P25. Hysteresivity increased in only P25. Methylprednisolone at 1 or 6 hours attenuated in vivo and in vitro mechanical changes in P25, whereas P10 parameters were similar to the control. Collagen increment was dose and time dependent. Elastic fibers increased in P25 and at 30 days in P10. Corticosteroid prevented collagen increment and avoided elastogenesis. In conclusion, methylprednisolone led to a complete maintenance of in vivo and in vitro respiratory mechanics in mild lesion, whereas it minimized the changes in tissue impedance and extracellular matrix in severe ALI. The beneficial effects of the early use of steroids in ALI remained unaltered at Day 30.

Paraquat (PQ)-induced pulmonary fibrosis increases exercise metabolic cost, reducing aerobic performance in rats

“…2). In other studies (Rocco et al, 2003;Silva et al 1998), data from the area of lung collapse were used as an indicator of the degree of pulmonary injury. In the chronmaintains the alveolar collapse, thereby reducing lung ventilation and decreasing gas exchange.…”

“…It is highly toxic to humans and animals, accumulating mainly in the lungs, liver, kidneys and heart. This herbicide has been widely used as an experimental model to study lung injury, especially diffuse alveolar damage, due to its low cost, rapid effect and simplicity of administration (Rocco et al, 2003;Silva and Saldiva, 1998). Moreover, the mecha--herbicide (Dasta, 1978).…”

Effects of rapamycin against paraquat-induced pulmonary fibrosis in mice

“…This is mainly because PQ selectively accumulates in the lungs, leading to irreversible pulmonary fibrosis. Previous studies have revealed that a combination of glucocorticoid and cyclophosphamide can improve the survival rate of PQ-poisoned patients or animal models, and reduce the pathological changes in the lung tissues, such as inflammatory cell infiltration, in the early stages of acute lung injury (ALI) (Rocco et al, 2003;Li et al, 2014), but this therapy does not have a significant effect in preventing progressive pulmonary fibrosis. Some other potential agents, such as docosahexaenoic acid (DHA) (Chen J. et al, 2013) and naringin (Chen Y. et al, 2013;Blanco-Ayala et al, 2014), have been shown to ameliorate PQ-induced pulmonary fibrosis in animal models.…”

Changes in the Respiratory System of Rats Exposed to the Herbicide Paraquat

“…There are several hypotheses to explain its alterations, one of which is due to the modification in the properties of alveolar surfactant and/or loss of lung capacity due to the presence of liquid on the alveolar surface (Gregory et al, 1991, Rocco et al, 2003. Another pathway is through the influence that the narrowing of the airways, resulting in what could be called a distortion of the lung parenchyma with the closure of small airways.…”

“…Another pathway is through the influence that the narrowing of the airways, resulting in what could be called a distortion of the lung parenchyma with the closure of small airways. In the first 24 h, fluid accumulation occurs in the interstitium and in the air spaces of the lung, leading to hypoxemia, decreased pulmonary compliance and increased respiratory work (Rocco et al, 2003).…”