[Enzyme replacement therapy of lysosomal storage diseases]. / Thérapies enzymatiques substitutives des maladies lysosomales.

Extraction and purification of an acid ß-glucosidase from human placenta (alglucerase) for the treatment of Gaucher disease, replaced a few years later by a recombinant enzyme (imiglucérase, Cerezyme(®)), has paved the way to the development of enzyme replacement therapies (ERT) for the treatment of lysosomal storage diseases (LSD) among which Fabry disease for which the long-term efficacy of the two currently available preparations (agalsidase alfa, Replagal(®) and Fabrazyme(®)) is still being investigated. Mucopolysaccharidosis (MPS) type I (Hurler and Scheie diseases), II (Hunter syndrome) and VI (Maroteaux-Lamy disease) also benefit from ERT using laronidase (Aldurazyme(®)), idursulfase (Elaprase(®)) and galsulfase (Naglazyme(®)), respectively. ERT reduces the hepatosplenomegaly and improves the physical and respiratory capacities of MPS patients with a globally acceptable safety profile although the possibility of infusion-associated should always be kept in mind. Alglucosidase alpha (Myozyme(®)) improves the cardiomyopathy and life expectancy of infants suffering from Pompe disease and is under evaluation for the treatment of the juvenile and adult forms of the disease. CNS involvement remains a major challenge for many LSD and innovative research and approaches are needed to address the fact that recombinant enzymes do not cross the blood-brain barrier and therefore are not expected to lead to any improvement in CNS damages, except if alternative routes such as intrathecal administration would be developed. Molecular chaperones (e.g. migalastat for Fabry disease) and inhibitors of glucosylceramide synthesis (e.g. eliglustat tartrate for Gaucher disease) are currently under investigation in various clinical trials.

Allele-specific amplification for the diagnosis of autosomal recessive spinal muscular atrophy.

The SMN1 gene is homozygously deleted for at least exon 7, interrupted or converted to a non-functional telomeric copy in most cases of proximal spinal muscular atrophies. The presence of a pseudogene hampers direct detection of the exon 7 deletion. We describe a method for the detection of the of exon 7 deletion, based on the amplification refractory mutation system (ARMS), in a multiplex PCR with fluorescent-labelled primers. The gene and pseudogene amplification products differ in the dye bound and in their size, which allows distinction of both products on electrophoresis. The pseudogene is used as an internal control, and this method gives a clear and specific pattern for the patients. Amplification is achieved with 30 cycles, and specificity is retained up to 40 cycles.

Immunoglobulin A levels in bronchial samples during mechanical ventilation and onset of nosocomial pneumonia in critically ill patients.

Local immunoglobulins play a key role in host defense against lung infection. We investigated the pattern of evolution of bronchial albumin, IgA, and IgG levels in ventilated ICU patients in relation to nosocomial pneumonia. Immunocompetent, critically ill patients underwent serial blood and bronchial protein determinations on Day 1 (intubation day), and on Days 3, 7, 10, and 14. The variations in proteins levels were compared with corresponding Day 1 values in the whole population, and between patients who developed lung infections (Group A) and the remaining population (Group B). Forty-four patients were included into the study. In the whole population, when compared with the baseline value, bronchial IgA/albumin ratio increased significantly (Day 3, +58%, p = 0.04); Day 14, +171%, p < 0.01), but serum IgA/albumin and serum and bronchial IgG/albumin ratios did not change significantly. In Group A, the increase in the IgA/albumin ratio was less than in Group B (Day 3, +15% versus +87%, p = 0.04; Day 14, +29% versus +210%, p < 0.01). No significant differences were observed between the two groups for bronchial and plasma albumin and IgG levels and for bronchial polymorphonuclear elastase levels. Bronchial IgA production was enhanced in ventilated patients. A reduction in this enhanced bronchial IgA production might account for the development of nosocomial pneumonia.