Biological impact of restrictive and liberal fluid strategies at low and high PEEP levels on lung and distal organs in experimental acute respiratory distress syndrome.

Background: Fluid regimens in acute respiratory distress syndrome (ARDS) are conflicting. The amount of fluid and positive end-expiratory pressure (PEEP) level may interact leading to ventilator-induced lung injury (VILI). We therefore evaluated restrictive and liberal fluid strategies associated with low and high PEEP levels with regard to lung and kidney damage, as well as cardiorespiratory function in endotoxin-induced ARDS. Methods: Thirty male Wistar rats received an intratracheal instillation of Escherichia coli lipopolysaccharide. After 24 h, the animals were anesthetized, protectively ventilated (VT = 6 ml/kg), and randomized to restrictive (5 ml/kg/h) or liberal (40 ml/kg/h) fluid strategies (Ringer lactate). Both groups were then ventilated with PEEP = 3 cmH2O (PEEP3) and PEEP = 9 cmH2O (PEEP9) for 1 h (n = 6/group). Echocardiography, arterial blood gases, and lung mechanics were evaluated throughout the experiments. Histologic analyses were done on the lungs, and molecular biology was assessed in lungs and kidneys using six non-ventilated animals with no fluid therapy. Results: In lungs, the liberal group showed increased transpulmonary plateau pressure compared with the restrictive group (liberal, 23.5 ± 2.9 cmH2O; restrictive, 18.8 ± 2.3 cmH2O, p = 0.046) under PEEP = 9 cmH2O. Gene expression associated with inflammation (interleukin [IL]-6) was higher in the liberal-PEEP9 group than the liberal-PEEP3 group (p = 0.006) and restrictive-PEEP9 (p = 0.012), Regardless of the fluid strategy, lung mechanical power and the heterogeneity index were higher, whereas birefringence for claudin-4 and zonula-ocludens-1 gene expression were lower in the PEEP9 groups. Perivascular edema was higher in liberal groups, regardless of PEEP levels. Markers related to damage to epithelial cells [club cell secreted protein (CC16)] and the extracellular matrix (syndecan) were higher in the liberal-PEEP9 group than the liberal-PEEP3 group (p = 0.010 and p = 0.024, respectively). In kidneys, the expression of IL-6 and neutrophil gelatinase-associated lipocalin was higher in PEEP9 groups, regardless of the fluid strategy. For the liberal strategy, PEEP = 9 cmH2O compared with PEEP = 3 cmH2O reduced the right ventricle systolic volume (37%) and inferior vena cava collapsibility index (45%). Conclusion: The combination of a liberal fluid strategy and high PEEP led to more lung damage. The application of high PEEP, regardless of the fluid strategy, may also be deleterious to kidneys.

Proposition of a novel animal model of systemic sclerosis induced by type V collagen in C57BL/6 mice that reproduces fibrosis, vasculopathy and autoimmunity.

BACKGROUND: Type V collagen (Col V) has the potential to become an autoantigen and has been associated with the pathogenesis of systemic sclerosis (SSc). We characterized serological, functional, and histopathological features of the skin and lung in a novel SSc murine model induced by Col V immunization. METHODS: Female C57BL/6 mice (n = 19, IMU-COLV) were subcutaneously immunized with two doses of Col V (125 µg) emulsified in complete Freund adjuvant, followed by two intramuscular boosters. The control group (n = 19) did not receive Col V. After 120 days, we examined the respiratory mechanics, serum autoantibodies, and vascular manifestations of the mice. The skin and lung inflammatory processes and the collagen gene/protein expressions were analyzed. RESULTS: Vascular manifestations were characterized by endothelial cell activity and apoptosis, as shown by the increased expression of VEGF, endothelin-1, and caspase-3 in endothelial cells. The IMU-COLV mice presented with increased tissue elastance and a nonspecific interstitial pneumonia (NSIP) histologic pattern in the lung, combined with the thickening of the small and medium intrapulmonary arteries, increased Col V fibers, and increased COL1A1, COL1A2, COL3A1, COL5A1, and COL5A2 gene expression. The skin of the IMU-COLV mice showed thickness, epidermal rectification, decreased papillary dermis, atrophied appendages, and increased collagen, COL5A1, and COL5A2 gene expression. Anti-collagen III and IV and ANA antibodies were detected in the sera of the IMU-COLV mice. CONCLUSION: We demonstrated that cutaneous, vascular, and pulmonary remodeling are mimicked in the Col V-induced SSc mouse model, which thus represents a suitable preclinical model to study the mechanisms and therapeutic approaches for SSc.

Neuroendocrine and biologic features of primary tumors and tissue in pulmonary large cell carcinomas.

BACKGROUND: Because biological behavior in lung tumors with neuroendocrine differentiation is highly dependent on cell death (apoptosis) and angiogenesis, p21(waf1/cip1) and microvessel density have been targeted as potentially useful tumor markers. We sought to validate the importance of p21(waf1/cip1) and microvessel density and study their interrelationship, analyzing clinical factors, subclassifications, and tumor and stromal markers. METHODS: We examined p21(waf1/cip1) and other markers in tissue from 61 patients with surgically excised large cell carcinomas. The amount of tumor staining for p21(waf1/cip1) and microvessel density was evaluated by immunohistochemistry and morphometry. The study outcome was survival time until death from recurrent lung cancer. RESULTS: Multivariate Cox model analysis demonstrated that after surgical excision, histologic subtypes were significantly related to survival time (p = 0.02), but quantitative staining of the tumor for p21(waf1/cip1) and microvessel density added prognostic information and these variables were more strongly prognostic than histologic subtype (p = 0.00). Cut points at the median staining of 3.5% and 3.0% for p21(waf1/cip1) and microvessel density, respectively, divided patients into two groups with distinctive survival times. Patients with p21(waf1/cip1) staining of more than 3.5% and microvessel density staining of more than 3.0% had a median survival time of 14 months. CONCLUSIONS: Tumor staining for p21(waf1/cip1) and microvessel density in resected large cell carcinomas and certain other types of lung tumors was strongly related to survival. Patients with more than 3.0% staining in their tumors were at high risk of death from lung cancer and may be an appropriate target for prospective studies of adjuvant chemotherapy after surgical resection.