Mechanisms of virus-induced asthma exacerbations: State-of-the-art. A GA2LEN and InterAirways document

Viral infections of the respiratory tract are the most common precipitants of acute asthma exacerbations. Exacerbations are only poorly responsive to current asthma therapies and new approaches to therapy are needed. Viruses, most frequently human rhinoviruses (RV), infect the airway epithelium, generate local and systemic immune responses, as well as neural responses, inducing inflammation and airway hyperresponsiveness. Using in vitro and in vivo experimental models the role of various proinflammatory or anti-inflammatory mediators, antiviral responses and molecular pathways that lead from infection to symptoms has been partly unravelled. In particular, mechanisms of susceptibility to viral infection have been identified and the bronchial epithelium appeared to be a key player. Nevertheless, additional understanding of the integration between the diverse elements of the antiviral response, especially in the context of allergic airway inflammation, as well as the interactions between viral infections and other stimuli that affect airway inflammation and responsiveness may lead to novel strategies in treating and/or preventing asthma exacerbations. This review presents the current knowledge and highlights areas in need of further research. © 2007 The Authors

Proliferating or Differentiating Stimuli Act on Different Lipid-dependent Signaling Pathways in Nuclei of Human Leukemia Cells

Previous results have shown that the human promyelocytic leukemia HL-60 cell line responds to either proliferating or differentiating stimuli. When these cells are induced to proliferate, protein kinase C (PKC)-βII migrates toward the nucleus, whereas when they are exposed to differentiating agents, there is a nuclear translocation of the α isoform of PKC. As a step toward the elucidation of the early intranuclear events that regulate the proliferation or the differentiation process, we show that in the HL-60 cells, a proliferating stimulus (i.e., insulin-like growth factor-I [IGF-I]) increased nuclear diacylglycerol (DAG) production derived from phosphatidylinositol (4,5) bisphosphate, as indicated by the inhibition exerted by 1-O-octadeyl-2-O-methyl-sn-glycero-3-phosphocholine and U-73122 (1-[6((17β-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl]-1H-pyrrole-2,5-dione), which are pharmacological inhibitors of phosphoinositide-specific phospholipase C. In contrast, when HL-60 cells were induced to differentiate along the granulocytic lineage by dimethyl sulfoxide, we observed a rise in the nuclear DAG mass, which was sensitive to either neomycin or propranolol, two compounds with inhibitory effect on phospholipase D (PLD)-mediated DAG generation. In nuclei of dimethyl sulfoxide-treated HL-60 cells, we observed a rise in the amount of a 90-kDa PLD, distinct from PLD1 or PLD2. When a phosphatidylinositol (4,5) bisphosphate-derived DAG pool was generated in the nucleus, a selective translocation of PKC-βII occurred. On the other hand, nuclear DAG derived through PLD, recruited PKC-α to the nucleus. Both of these PKC isoforms were phosphorylated on serine residues. These results provide support for the proposal that in the HL-60 cell nucleus there are two independently regulated sources of DAG, both of which are capable of acting as the driving force that attracts to this organelle distinct, DAG-dependent PKC isozymes. Our results assume a particular significance in light of the proposed use of pharmacological inhibitors of PKC-dependent biochemical pathways for the therapy of cancer disease

Prediction of worsening of skin fibrosis in patients with diffuse cutaneous systemic sclerosis using the EUSTAR database

Objectives To identify predictive parameters for the progression of skin fibrosis within 1 year in patients with diffuse cutaneous SSc (dcSSc). Methods An observational study using the EUSTAR database was performed. Inclusion criteria were dcSSc, American College of Rheumatology (ACR) criteria fulfilled, modified Rodnan skin score (MRSS) ≥7 at baseline visit, valid data for MRSS at 2nd visit, and available follow-up of 12±2 months. Worsening of skin fibrosis was defined as increase in MRSS >5 points and ≥25% from baseline to 2nd visit. In the univariate analysis, patients with progressive fibrosis were compared with non-progressors, and predictive markers with p<0.2 were included in the logistic regression analysis. The prediction models were then validated in a second cohort. Results A total of 637 dcSSc patients were eligible. Univariate analyses identified joint synovitis, short disease duration (≤15 months), short disease duration in females/patients without creatine kinase (CK) elevation, low baseline MRSS (≤22/51), and absence of oesophageal symptoms as potential predictors for progressive skin fibrosis. In the multivariate analysis, by employing combinations of the predictors, 17 models with varying prediction success were generated, allowing cohort enrichment from 9.7% progressive patients in the whole cohort to 44.4% in the optimised enrichment cohort. Using a second validation cohort of 188 dcSSc patients, short disease duration, low baseline MRSS and joint synovitis were confirmed as independent predictors of progressive skin fibrosis within 1 year resulting in a 4.5-fold increased prediction success rate. Conclusions Our study provides novel, evidence-based criteria for the enrichment of dcSSc cohorts with patients who experience worsening of skin fibrosis which allows improved clinical trial design