Study Status: Completed
Recruit Status: Completed
Study Type: Interventional
Official Title: The Functional Consequences of the CTNS-deletion for the TRPV1-receptor in Cystinosis Patients
Brief Summary:
Cystinosis is a rare autosomal recessive disorder, characterized by the abnormal accumulation of cystine in the lysosomes. Cystinosis is mostly caused by mutations in the cystinosin gene (CTNS). The major mutation, which is present in almost 50% of the cystinosis patients, is a 57-kb deletion. This deletion removes the first 9 exons and a part of exon 10 of the CTNS gene. Exon 10 of the CTNS gene is a upstream 5' region that encodes for the CARKL gene and also for the first two noncoding exons of the transient receptor potential channel, vanilloid subfamily member 1 (TRPV1) gene.
TRPV1 belongs to the transient receptor potential (TRP) superfamily of cation channels. TRPV1 is primarily expressed in sensory nerves and is activated by heating (>43°C) and a wide range of chemical stimuli. One of these chemical stimuli is capsaicin, the pungent ingredient in hot chilli peppers. The effect of binding of the exogenous ligand capsaicin with the TRPV1 receptor is well known to provoke the release of a number of bioactive substances including calcitonin gene-related peptide (CGRP). These substances, in turn, act on target cells in the surrounding tissue such as mast cells, immune cells and vascular smooth muscle cells. The resulting response is characterized by redness and warmth (secondary to vasodilatation), swelling (secondary to plasma extravasation) and allodynia (i.e. hypersensitivity to heat and touch secondary to alterations in the excitability of primary sensory neurons).
The present study wants to test the following hypotheses:
(i) The DBF response to topical applied capsaicin is decreased in cystinosis patients, compared to matched control subjects.
(ii) The skin sensitivity response after topical applied capsaicin