Gene expression profiling of target genes in ventilator-induced lung injury

Abstract

.-In the lungs, high-pressure mechanical ventilation induces an inflammatory response similar to that observed in acute respiratory distress syndrome. To further characterize these responses and to compare them with classical inflammatory pathways, we performed gene expression profiling analysis of 20,000 mouse genes in isolated blood-free (to exclude genes from sequestered leukocytes) perfused mouse lungs exposed to lowpressure ventilation (10 cmH2O), high-pressure ventilation (25 cmH2O, overventilation), and LPS treatment. A large number of inflammatory and apoptotic genes were increased by both overventilation and LPS. However, certain growth factor-related genes, as well as genes related to development, cellular communication, and the cytoskeleton, were only regulated by overventilation. We validated and confirmed increased mRNA expression pattern of five genes (amphiregulin, gravin, Nur77, Cyr61, interleukin-11) by real-time PCR; furthermore, we confirmed increased protein expression of amphiregulin by immunohistochemistry and immunoblotting assays. These genes represent novel candidate genes in ventilator-induced lung injury. overventilation; acute respiratory distress syndrome; gene expression analysis DESPITE INTENSIVE INVESTIGATIONS, the mortality of acute respiratory distress syndrome (ARDS) remains high (1a). Patients at risk for ARDS as well as ARDS patients themselves (13, 20) are prone to ventilator-induced lung injury (VILI) and benefit from low tidal volume ventilation (1a). Clinical and animal studies suggest that the release of proinflammatory cytokines and other factors during alveolar overdistension contributes to lung injury in VILI (1a,9,12,17). One important insight in this area is that ventilation with high distending pressures (overventilation) may activate, if by different signaling mechanisms, canonical inflammation pathways that also become activated by well-known proinflammatory stimuli such as bacterial endotoxin (31). For instance, both overventilation and LPS activate nuclear factor-B (NF-B) (17, 32) and mitogen-activated protein kinase (MAPK) (33), which subsequently activate chemokines, cytokines, and adhesion molecules (32). One important objective is to identify genes that are specifically activated by overventilation but not by endotoxin. Such genes might provide specific targets to reduce the side effects of mechanical ventilation without interfering with the innate immune system. Microarray technology allows us to study gene expression of a significant fraction of the genome and has been used to identify candidate genes critical to a variety of lung diseases including chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, lung cancer, pulmonary hypertension, and lung transplantation (2,8,24,36,37). However, application of this approach to ventilator-induced gene expression in vivo is complicated by at least two factors: 1) in intact noninjured animals, alveolar overdistension is limited by both the chest wall and adjacent alveoli, and 2) infiltrating inflam...

Genetic and Pharmacologic Evidence Links Oxidative Stress to Ventilator-induced Lung Injury in Mice

“…Our results, consistent with previous reports (11,15,(33)(34)(35), demonstrated an inducible expression of a majority of VALI genes in wild-type (Nrf2 1/1 ) mice (Table 1); however, we found a lack of induction of several of these genes in the lungs of Nrf2 2/2 mice. For example, several genes that modulate tissue matrix remodeling and blood coagulation were significantly induced in Nrf2 1/1 mice but not in Nrf2 2/2 mice.…”

“…The accumulation of neutrophils in the lung tissue can also lead to enhanced levels of inflammatory cytokines, which play fundamental roles in the development of lung pathogenesis, including VILI (9,10). Recent expression profiling using injurious and noninjurious MV in the presence and absence of inflammatory stimuli revealed the involvement of a complex network of genes encoding for matrix remodeling proteins, proinflammatory cytokines, and various transcription factors in VILI (11)(12)(13)(14)(15). The exact molecular mechanisms controlling the expression levels of these genes in response to MV and their contribution to the development or susceptibility to VILI are unclear.…”

Conserved responses to trichostatin A in rodent lungs exposed to endotoxin or stretch

“…First, the findings further corroborate our previous conclusion that the pulmonary responses to overventilation and LPS are remarkably similar [31,32], which is most likely explained by their activating a canonical inflammation pathway [33]. As a corollary of this, the genes studied herein are likely part of this canonical pathway.…”

Pediatric acute lung injury

“…Distinct gene candidates have been identified which are associated with lung injury induced by overdistention as a possible cause for VILI [159]. As one of the novel mechanisms, Woesten et al found increased ACE activity in bronchoalveolar lavage fluid (BALF) of mechanically ventilated rats triggering inflammation and apoptosis within hours.…”