The European Concerted Action NCL Clinical Case Registry

Two novel CLN5 mutations in a Portuguese patient with vLINCL: insights into molecular mechanisms of CLN5 deficiency

The neuronal ceroid-lipofuscinoses are the most common neurodegenerative disorders in childhood characterized by progressive blindness, epilepsy, brain atrophy, and premature death. Based on the age at onset, disease progression and ultrastructural features three classical (infantile, late-infantile, and juvenile) and three variant late-infantile forms are generally distinguished (Finnish variant, Costa Rican variant, and epilepsy with progressive motor retardation). The Finnish variant late-infantile form has been associated with CLN5 gene defects, with only five mutations described to date. We report a patient with vLINCL/CLN5 who represents the first evidence of the disease in the Portuguese population. Mutational screening revealed the previously described missense mutation c.835G>A (D279N) inherited from the mother, and two novel mutations, c.565C>T (Q189X) and c.335G>C (R112P) from paternal and maternal inheritance, respectively. Based on data here reported: (i) the number of possible mutations in CLN5 gene is now 7; (ii) the CLN5 Portuguese case represents the third description of the disease outside northern Europe; (iii) the CLN5/mRNA expression level reduced to 45% supports the existence of one mRNA non-producing allele, further noticeable at the protein level; (iv) Western blotting data using a specific antibody to human CLN5p provided evidence for the presence of four integral membrane isoforms in human fibroblasts; (v) data from differential expression of CLN2, CLN3, and CLN5 suggest down-regulation of CLN3 gene expression in CLN2 and CLN5-deficient human patients and this observation strengths the hypothesis of functional redundancy of the CLN system.

Surfactant with SP-B and SP-C analogues improves lung function in surfactant-deficient rats

The use of mammalian lung surfactant extracts has sharply reduced mortality and morbidity from respiratory distress syndrome in premature infants. Synthesis of surfactant protein B and C (SP-B and SP-C) analogues may lead the way to a synthetic surfactant preparation. Dimeric SP-B(1-25) (dSP-B(1-25)) is based on the N-terminal domain of human SP-B and SP-Cfc is a modified human SP-C in which a single phenylalanine is substituted for a palmitoylated cysteine residue in the N-terminal segment (Phe-4 > Cys-4 variant). We tested the effects of synthetic surfactants with 1 or 2% dSP-B(1-25) and 1% SP-Cfc on lung function in surfactant-deficient rats. Four experimental surfactant preparations were prepared by mixing 1% dSP-B(1-25), 2% dSP-B(1-25), 1% dSP-B(1-25) +1% SP-Cfc, and 2% dSP-B(1-25) +1% SP-Cfc with phospholipids (PL). PL and Survanta, a bovine lung extract, were controls. Groups of 8 rats were ventilated, lavaged until surfactant deficiency, and treated with 100 mg/kg surfactant. Arterial blood gas values and dynamic compliance were measured every 15 min and after 2 h of ventilation, the rats were killed and pressure-volume curves performed. Oxygenation improved quickly after instillation of surfactant with synthetic peptides and Survanta. Oxygenation and lung volumes were consistently higher in the 2% than in the 1% dSP-B(1-25) groups. Addition of 1% SP-Cfc to the synthetic surfactants further improved oxygenation and lung volume, but to a lesser extent than increasing the dSP-B(1-25) content from 1 to 2%. These data indicate that improvements in oxygenation and lung volume in lavaged rats are dependent on the concentration of dSP-B(1-25) in the surfactant preparation and that the presence of SP-Cfc has a relative minor effect on these parameters.

Treatment of acute (Adult) respiratory distress syndrome. The holy grail of surfactant therapy

The treatment of neonatal respiratory distress syndrome with surfactant represents a successful culmination of decades of basic and clinical research. In many babies, respiratory distress syndrome is a relatively pure expression of surfactant deficiency. Acute respiratory distress syndrome (ARDS) is a more common disease that is most frequently seen in adults, but the processes are common to lung injuries in newborns and children as well. While some impairment of production and secretion of surfactant constituents may be present in ARDS, surfactant inactivation is probably a more important factor in this disease. Until recently, surfactants available for human use have been easily susceptible to inactivation and this may explain why they have been less successful for treatment of ARDS than for neonatal respiratory distress syndrome. This review outlines recent information on surfactant inactivation and describes initiatives that may result in 'inactivation-proof' surfactants that may be of increased benefit in ARDS.