Fas expression in conjunctival epithelial cells of patients with cystic fibrosis

Role of CD95 in pulmonary inflammation and infection in cystic fibrosis

Cystic fibrosis is caused by a defective expression of the cystic fibrosis transmembrane conductance regulator (Cftr) gene, which results in chronic pulmonary inflammation and infections. The pathophysiological mechanisms by which these changes are induced in the lungs of patients with cystic fibrosis require definition. This study found that Cftr deficiency in mice results in the upregulation and activation of CD95. CD95 activation is caused by increased ceramide concentrations in cystic fibrosis lungs, as revealed by genetic modifications that normalize pulmonary ceramide concentrations. The activation of CD95 in cystic fibrosis lungs further increases pulmonary ceramide levels and results in a vicious feedback cycle of CD95 activation and ceramide accumulation. Genetic studies reveal that CD95 is crucially involved in the induction of aseptic inflammation, an increase in the bronchial cell death rate, and an increased susceptibility to infection of Cftr-deficient mice. All of these pathologies are partially corrected by heterozygosity of CD95 in Cftr-deficient mice. These findings identify CD95 as an important regulator of lung functions in cystic fibrosis and suggest that CD95 may be a novel target for treating cystic fibrosis.

Lymphocyte apoptosis in children with central nervous system tuberculosis: a case control study

Background

Studies of the apoptosis mechanisms involved in the pathogenesis of tuberculosis have suggested that Mycobacterium tuberculosis can actively interfere with the apoptosis of infected cells. In vivo studies have been performed in adult populations but have not focused on this process in children. In the present study, we analyzed spontaneous T lymphocyte (PBT) apoptosis in the peripheral blood of children with central nervous system tuberculosis (CNS TB), before and after chemotherapy, and compared the results with healthy controls.

Methods

A case-control study was conducted from January 2002 to June 2009. It included 18 children with CNS TB and 17 healthy controls. Spontaneous apoptosis of PBTs, including CD4⁺, CD8⁺ and CD8⁺/CD28⁺ T cells, was evaluated after 24 and 72 h of culture in complete medium, using the Annexin V detection test. Analysis was conducted before and after chemotherapy, and expression of the apoptotic markers CD95 (Fas) and Fas ligand (FasL) was evaluated.

Results

Higher percentages of apoptotic T cells and CD4 lymphocytes were isolated from children with acute phase CNS TB than from children in the control group (p < 0.05). This difference significantly decreased after 60 days of specific treatment. In children with CNS TB, high levels of Fas ligand expression were detected in lymphocyte populations, associated with a high percentage of Fas positive cells, before and after treatment. In contrast to the CD4+ apoptosis profile, we did not find any significant difference in total CD8⁺ cell apoptosis between children with acute phase disease and the control group. However, the percentage of apoptotic CD8⁺/CD28⁺ T cells was significantly higher in the children with acute phase disease than in the healthy controls.

Conclusions

Our findings indicate that CNS TB in pediatric patients increases the sensitivity of CD4 and CD8⁺/CD28⁺ T cells to apoptosis, suggesting a hypoergic status of this infection. This could play a key role in the immunopathogenesis of this complicated form of TB. Interestingly, specific chemotherapy is able to normalize both apoptosis sensitivity and T-cell activation.