Lipopolysaccharide-induced lung injury is independent of serum vitamin D concentration.

Vitamin D deficiency is increasing in incidence around the world. Vitamin D, a fat-soluble vitamin, has documented effects on the innate and adaptive immune system, including macrophage and T regulatory (Treg) cell function. Since Treg cells are important in acute lung injury resolution, we hypothesized that vitamin D deficiency increases the severity of injury and delays injury resolution in lipopolysaccharide (LPS) induced acute lung injury. Vitamin D deficient mice were generated, using C57BL/6 mice, through diet modification and limited exposure to ultraviolet light. At 8 weeks of age, vitamin D deficient and sufficient mice received 2.5 g/kg of LPS or saline intratracheal. At 1 day, 3 days and 10 days, mice were anesthetized and lung elastance measured. Mice were euthanized and bronchoalveolar lavage fluid, lungs and serum were collected. Ex vivo neutrophil chemotaxis was evaluated, using neutrophils from vitamin D sufficient and deficient mice exposed to the chemoattractants, KC/CXCL1 and C5a, and to bronchoalveolar lavage fluid from LPS-exposed mice. We found no difference in the degree of lung injury. Leukocytes were mildly decreased in the bronchoalveolar fluid of vitamin D deficient mice at 1 day. Ex-vivo, neutrophils from vitamin D deficient mice showed impaired chemotaxis to KC but not to C5a. Vitamin D deficiency modestly impairs neutrophil chemotaxis; however, it does not affect lung injury or its resolution in an LPS model of acute lung injury.

Noninjurious mechanical ventilation activates a proinflammatory transcriptional program in the lung.

Mechanical ventilation is a life-saving intervention in patients with respiratory failure. However, human and animal studies have demonstrated that mechanical ventilation using large tidal volumes (>or=12 ml/kg) induces a potent inflammatory response and can cause acute lung injury. We hypothesized that mechanical ventilation with a "noninjurious" tidal volume of 10 ml/kg would still activate a transcriptional program that places the lung at risk for severe injury. To identify key regulators of this transcriptional response, we integrated gene expression data obtained from whole lungs of spontaneously breathing mice and mechanically ventilated mice with computational network analysis. Topological analysis of the gene product interaction network identified Jun and Fos families of proteins as potential regulatory hubs. Electrophoretic mobility gel shift assay confirmed protein binding to activator protein-1 (AP-1) consensus sequences, and supershift experiments identified JunD and FosB as components of ventilation-induced AP-1 binding. Specific recruitment of JunD to the regulatory region of the F3 gene by mechanical ventilation was confirmed by chromatin immunoprecipitation assay. In conclusion, we demonstrate a novel computational framework to systematically dissect transcriptional programs activated by mechanical ventilation in the lung, and show that noninjurious mechanical ventilation initiates a response that can prime the lung for injury from a subsequent insult.

Current controversy related to glucocorticoid and insulin therapy in the intensive care unit.

OBJECTIVE: To review the controversy related to the widespread use of intensive insulin treatment (IIT) to maintain normoglycemia and of glucocorticoid replacement therapy in patients with sepsis in the intensive care unit (ICU). METHODS: We performed a MEDLINE search of the literature using a combination of words (critical/intensive care, endocrinology/endocrine, glucocorticoid/adrenal, insulin) to identify original studies and reviews on glucocorticoid therapy and IIT in the ICU. RESULTS: Glucocorticoid replacement therapy is advocated for patients with sepsis who have relative adrenal insufficiency. The current definition of relative adrenal insufficiency is poorly supported, and validated endocrine criteria that consistently identify ICU patients likely to benefit from glucocorticoid therapy are not yet available. IIT benefits postoperative patients at high risk of infection and patients who remain in the ICU more than 3 days. Potential harm caused by early IIT administration in medical ICU patients remains controversial. The role of early nutritional supplementation in major studies about IIT is largely unexplored. Improvements in insulin infusion protocols are needed to reduce the risk of hypoglycemia related to IIT. CONCLUSION: Endocrine therapy in the ICU is entering a new era. Controversies remain related to glucocorticoid and insulin therapy even as interest in new, and old, endocrine therapies is being revived.