Isolated Lung Perfusion in the Management of Acute Respiratory Distress Syndrome

Transvenous Pulmonary Chemoembolization and Optional Microwave Ablation for Colorectal Lung Metastases

(1) Purpose: To evaluate tumor response and survival of patients with colorectal pulmonary metastases treated by transvenous pulmonary chemoembolization (TPCE) alone with palliative intent or TPCE followed by microwave ablation (MWA) with potentially curative intent. (2) Material and methods: A total of 164 patients (64 women and 100 men; mean age: 61.8 ± 12.7 years) with unresectable colorectal lung metastases and not responding to systemic chemotherapy, who either received repetitive TPCE (Group A) or TPCE followed by MWA (Group B), were retrospectively enrolled. The revised response evaluation criteria in solid tumors were used to assess treatment response in Group A. The oncological response in Group B was divided into local tumor progression (LTP) and intrapulmonary distant recurrence (IDR) after MWA. (3) Results: The 1-, 2-, 3-, and 4-year survival rates were 70.4%, 41.4%, 22.3%, and 5%, respectively, for all patients. In Group A; the rates of stable disease; progressive disease; and partial response were at 55.4%, 41.9%, and 2.7%, respectively. The rates of LTP and IDR were 3.8%, and 63.5%, respectively, in Group B. Conclusion: TPCE is an effective treatment for colorectal lung metastases, which can be performed alone or combined with MWA.

Steen solution protects pulmonary microvascular endothelial cells and preserves endothelial barrier after lipopolysaccharide-induced injury

OBJECTIVES

Acute respiratory distress syndrome represents the devastating result of acute lung injury, with high mortality. Limited methods are available for rehabilitation of lungs affected by acute respiratory distress syndrome. Our laboratory has demonstrated rehabilitation of sepsis-injured lungs via normothermic ex vivo and in vivo perfusion with Steen solution (Steen). However, mechanisms responsible for the protective effects of Steen remain unclear. This study tests the hypothesis that Steen directly attenuates pulmonary endothelial barrier dysfunction and inflammation induced by lipopolysaccharide.

METHODS

Primary pulmonary microvascular endothelial cells were exposed to lipopolysaccharide for 4 hours and then recovered for 8 hours in complete media (Media), Steen, or Steen followed by complete media (Steen/Media). Oxidative stress, chemokines, permeability, interendothelial junction proteins, and toll-like receptor 4-mediated pathways were assessed in pulmonary microvascular endothelial cells using standard methods.

RESULTS

Lipopolysaccharide treatment of pulmonary microvascular endothelial cells and recovery in Media significantly induced reactive oxygen species, lipid peroxidation, expression of chemokines (eg, chemokine [C-X-C motif] ligand 1 and C-C motif chemokine ligand 2) and cell adhesion molecules (P-selectin, E-selectin, and vascular cell adhesion molecule 1), permeability, neutrophil transmigration, p38 mitogen-activated protein kinase and nuclear factor kappa B signaling, and decreased expression of tight and adherens junction proteins (zonula occludens-1, zonula occludens-2, and vascular endothelial-cadherin). All of these inflammatory pathways were significantly attenuated after recovery of pulmonary microvascular endothelial cells in Steen or Steen/Media.

CONCLUSIONS

Steen solution preserves pulmonary endothelial barrier function after lipopolysaccharide exposure by promoting an anti-inflammatory environment via attenuation of oxidative stress, toll-like receptor 4-mediated signaling, and conservation of interendothelial junctions. These protective mechanisms offer insight into the advancement of methods for in vivo lung perfusion with Steen for the treatment of severe acute respiratory distress syndrome.

Endothelial Transient Receptor Potential V4 Channels Mediate Lung Ischemia-Reperfusion Injury

BACKGROUND

Lung ischemia-reperfusion injury (IRI), involving severe inflammation and edema, is a major cause of primary graft dysfunction following transplant. Activation of transient receptor potential vanilloid 4 (TRPV4) channels modulates vascular permeability. Thus, this study tests the hypothesis that endothelial TRPV4 channels mediate lung IRI.

METHODS

C57BL/6 wild-type (WT), TRPV4^-/-, tamoxifen-inducible endothelial TRPV4 knockout (TRPV4_EC^-/-), and tamoxifen-treated control (TRPV4^fl/fl) mice underwent lung IR using a left lung hilar-ligation model (n≥6 mice/group). WT mice were also treated with a TRPV4-specific inhibitor (GSK2193874; 1mg/kg) (WT+GSK219). Partial pressure of oxygen (PaO₂), edema (wet-to-dry weight ratio), compliance, neutrophil infiltration, and cytokine concentrations in bronchioalveolar lavage fluid were assessed. Pulmonary microvascular endothelial cells (PMVECs) were characterized in vitro following exposure to hypoxia-reoxygenation.

RESULTS

Compared to WT, PaO₂ following IR was significantly improved in TRPV4^-/- mice (133.1±43.9 vs 427.8±83.1 mmHg, p<0.001) and WT+GSK219 mice (133.1±43.9 vs 447.0±67.6 mmHg, p<0.001). Pulmonary edema and neutrophil infiltration were also significantly reduced after IR in TRPV4^-/- and WT+GSK219 mice versus WT. TRPV4_EC^-/- mice following IR demonstrated significantly improved oxygenation versus control (109.2±21.6 vs 405.3±41.4 mmHg, p<0.001) as well as significantly improved compliance, and significantly less edema, neutrophil infiltration and proinflammatory cytokine production (TNF-α, CXCL1, IL-17, IFN-γ). Hypoxia-reoxygenation-induced permeability and CXCL1 expression by PMVECs was significantly attenuated by TRPV4 inhibitors.

CONCLUSIONS

Endothelial TRPV4 plays a key role in vascular permeability and lung inflammation following IR. TRPV4 channels may be a promising therapeutic target to mitigate lung IRI and decrease the incidence of primary graft dysfunction following transplant. (Word Count: 249/250).