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As the threshold nucleated cell dose for one-unit umbilical cord blood (UCB) in adults has not to date been firmly established, we prospectively compared one- vs two-unit UCB transplantation after reduced intensity conditioning (RIC) in adult patients with hematological malignancies. Study design specified one-UCB unit if the cryopreserved total nucleated cell (TNC) dose was ⩾2.5 × 10 7 /kg recipient weight, otherwise two units matched at minima of 4/6 HLA loci to the patient and 3/6 to each other were infused. A total of 27 patients received one unit; 23 patients received two units. Median time to ANC >500/μL was 24 days (95% confidence interval 22–28 days), 25 days for one unit and 23 days for two units ( P =0.99). At day 100, ANC >500/μL was 88.4 and 91.3% in the one- and two-unit groups ( P =0.99), respectively. Three-year EFS was 28.6% and 39.1% in the one- and two-unit groups ( P =0.71), respectively. Infusion of two units was associated with a significantly lower relapse risk, 30.4% vs 59.3% ( P =0.045). Infused cell doses (TNC, CD3 + , CD34 + and CD56 + CD3 neg ) did not impact on engraftment, OS or EFS. Taken together, one-unit UCB transplantation with a threshold cell dose ⩾2.5 × 10 7 /kg recipient weight after RIC is a viable option for adults, although infusion of two units confers a lower relapse incidence.

Microbial lung infections are the major cause of morbidity and mortality in the hereditary metabolic disorder cystic fibrosis, yet the molecular mechanisms leading from the mutation of cystic fibrosis transmembrane conductance regulator (CFTR) to lung infection are still unclear. Here, we show that ceramide age-dependently accumulates in the respiratory tract of uninfected Cftr -deficient mice owing to an alkalinization of intracellular vesicles in Cftr -deficient cells. This change in pH results in an imbalance between acid sphingomyelinase (Asm) cleavage of sphingomyelin to ceramide and acid ceramidase consumption of ceramide, resulting in the higher levels of ceramide. The accumulation of ceramide causes Cftr -deficient mice to suffer from constitutive age-dependent pulmonary inflammation, death of respiratory epithelial cells, deposits of DNA in bronchi and high susceptibility to severe Pseudomonas aeruginosa infections. Partial genetic deficiency of Asm in Cftr −/− Smpd1 +/− mice or pharmacological treatment of Cftr -deficient mice with the Asm blocker amitriptyline normalizes pulmonary ceramide and prevents all pathological findings, including susceptibility to infection. These data suggest inhibition of Asm as a new treatment strategy for cystic fibrosis.

Cystic fibrosis is caused by defects in the cystic fibrosis transmembrane conductance regulator gene, which codes for a chloride channel, but the role of this chloride channel in inflammation induced by lung infection with Pseudomonas aeruginosa remains to be defined. We tested the hypothesis that loss of this chloride channel alone is sufficient to cause excessive inflammation in response to inflammatory stimuli. We investigated the response of cystic fibrosis and wild-type mice to mucoid P. aeruginosa administered by insufflation. The host responses measured included survival, weight change, lung morphometry, bacterial clearance, and inflammatory mediators, and cell counts were assessed in bronchoalveolar lavage fluid. Depending on the dose administered and frequency of dosing, cystic fibrosis mice experienced significantly higher mortality rates, greater weight loss, higher lung pathology scores, and higher inflammatory mediator and neutrophil levels compared with wild-type mice, even after the bacteria had been cleared. Surprisingly, bacteria were cleared just as rapidly in cystic fibrosis mice as in wild-type mice, and sepsis was not observed. Chronic lung infections could not be established with mucoid P. aeruginosa in either cystic fibrosis or wild-type mice. Absence of this chloride channel alone appears sufficient for exaggerated inflammation and excess mortality compared with wild-type controls in the face of mucoid P. aeruginosa lung infection. To establish chronic infection, additional factors such as bacterial trapping or poor clearance may be required.

A mouse model of chronic Pseudomonas-induced bronchopulmonary inflammation that mimics chronic cystic fibrosis (CF) lung disease was employed to determine whether this inflammatory milieu influences immune responses to adenoviral vectors. Pseudomonas-infected and control mice were inoculated intranasally with a second-generation type 2 adenovirus (Ad2) vector (Ad2/βgal-2). After 3 weeks, serum and airway Ad2-specific antibodies and Ad2 vector-directed, cytotoxic T-lymphocyte (CTL) activity in splenocytes were measured. No differences in humoral immunity were observed between Pseudomonas-infected mice and controls. However, there was a two- to three-fold increase in Ad-specific CTL activity in the Pseudomonas-infected mice compared to control mice. MHC class I-dependent antigen presentation by antigen-presenting cells (APC) from lungs of Pseudomonas-infected mice was also significantly increased compared to APC from control mice, suggesting a mechanism that may contribute to increased Ad-specific CD8+ CTL responses. It was concluded that Ad-specific CTL activity is enhanced in the setting of pre-existing chronic Pseudomonas-induced lung inflammation similar to CF lung disease, and that increased antigen presentation via MHC class I in this setting may be one underlying mechanism. These findings underscore the importance of considering the influence of the disease milieu when evaluating modes of gene therapy for such diseases in animal models.

As the threshold nucleated cell dose for single unit umbilical cord blood (UCB) in adults has not to date been firmly established, we prospectively compared single vs. 2-unit UCB transplantation after reduced intensity conditioning (RIC) in adult patients with hematologic malignancies. Study design specified one UCB unit if the cryopreserved total nucleated cell (TNC) dose was ≥2.5×107/kg recipient weight, otherwise 2-units matched at minimum 4/6 HLA loci to the patient and 3/6 to each other were infused. Twenty-seven patients received 1 unit; 23 patients received 2 units. Median time to absolute neutrophil count (ANC) >500/μL was 24 days (95% CI 22–28 days), 25 days for 1-unit and 23 days for 2-units (p=0.99). At day 100, ANC >500/μL was 88.4% and 91.3% in the 1 and 2-unit groups (p=0.99), respectively. Three-year event free survival (EFS) was 28.6% and 39.1% in the 1 and 2-unit groups (p=0.71), respectively. Infusion of 2 units was associated with significantly lower relapse risk, 30.4% vs. 59.3% (p=0.045). Infused cell doses (TNC, CD3+, CD34+, CD56+CD3neg) did not impact engraftment, overall survival (OS), or EFS. Taken together, single unit UCB transplantation with threshold cell dose ≥2.5×107/kg recipient weight after RIC is a viable option for adults, although infusion of 2 units confers a lower relapse incidence.