Photodynamic Therapy

This book is dedicated to a topic related to the effects of photodynamic therapy organized by Biomedicines in 2022 (https://www.mdpi.com/topics/photodynamic_therapy). In medicine, the use of photodynamic therapy for the treatment of oncological and non-oncological diseases has been widely documented and well codified. In dermatology, the use varies from oncological to the treatment of chronic wounds, as well as in cosmetology for photo-rejuvenation. The 19 manuscripts published in this book cover all aspects of this therapy, including the discovery of new natural and synthetic photosensitizers, biomaterials and nanotechnology, in vitro and in vivo studies, and clinical trials

A Genetic and Functional Investigation of Inherited Neuropathies: Charcot-Marie Tooth Disease and Brown-Vialetto-Van Laere Syndrome

Charcot-Marie-Tooth (CMT) disease and Brown-Vialetto-Van Laere syndrome (BVVL) are two inherited neuropathies. Although most CMT type 1A patients carry the same sized duplication containing the peripheral myelin protein 22 (PMP22) gene, they present with a wide range of severities both within and between families. Some CMT1A patients exhibit chronic inflammatory demyelinating polyneuropathy (CIDP)-like features. An association study was performed in a CMT1A and a CIDP cohort to identify the genetic factors modifying the CMT1A phenotype. Variants associated with CIDP and/or with autoimmune/inflammatory diseases were determined to be unlikely to modulate disease severity in CMT1A, or to contribute to CMT1A pathogenesis. A susceptibility locus for CIDP was identified in the PXK gene. CMT1 genes were screened in CMT1 patients from the UK, Greece and Russia, thereby establishing mutation frequencies and expanding phenotype-genotype correlations. Some cases of CMT1 remain without a genetic diagnosis; two potential CMT1 candidate genes were identified by exome sequencing in two families. The genetic causes of selected canine neuropathies were investigated and several CMT genes were ruled out. BVVL is a rare, recessive motor neurone disease (MND) with early onset; a severe sensory-motor neuropathy is part of the phenotype. Mutations have been found in genes encoding riboflavin transporters, leading to flavin deficiency. To characterise the disease and facilitate early access to therapy, the riboflavin transporter genes were screened in patients with BVVL-like phenotypes; SLC52A2 mutations were most common. A candidate gene for complex axonal neuropathy resembling BVVL was uncovered by exome sequencing. Riboflavin and its active metabolites play a role in energy metabolism. Three cell models were used to investigate BVVL in vitro: patient fibroblasts, as well as a neuroblastoma cell line and mouse motor neurones in which one of the riboflavin transporters was knocked down. Mitochondrial dysfunction was suggested as a potential pathway leading to neuronal damage in BVVL

In vitro Metabolic Studies of Dopamine Synthesis and the Toxicity of L-DOPA in Human Cells

This work is divided in two parts. In the first, I investigated the effects of 2,3- dihydroxy-L-phenylalanine (L-DOPA) on the metabolism of human tyrosine hydroxylase (TH)-positive neuronal LUHMES cells. L-DOPA is the gold standard treatment for Parkinson’s disease (PD) and its effects on cellular metabolism are controversial. It induced a re-routing of intracellular carbon supplies. While glutamine contribution to tricarboxylic acid (TCA) cycle intermediates increased, glucose contribution to the same metabolites decreased. Carbon contribution from glucose was decreased in lactate and was compensated by an increased pyruvate contribution. Pyruvate reacted with hydrogen peroxide generated during the auto-oxidation of L-DOPA and lead to an increase of acetate in the medium. In the presence of L-DOPA, this acetate was taken up by the cells. In combination with an increased glutamate secretion, all these results seem to point towards a mitochondrial complex II inhibition. In the second part of this work, I studied and compared dopamine (DA)-producing in vitro systems. First, I compared gene and protein expression of catecholamine (CA)- related genes. Then, I performed molecular engineering to increase TH expression in LUHMES and SH-SY5Y cells. This was sufficient to induce DA production in SH-SY5Y, but not in LUHMES cells, indicating that TH expression is not sufficient to characterize dopaminergic neurons. Therefore I used SH-SY5Y cells overexpressing TH to study substrates for DA production. Upon overexpression of aromatic amino acid decarboxylase (AADC), LUHMES cells produced DA after L-DOPA supplementation. This model was useful to study L-DOPA uptake in LUHMES cells and I showed that L-DOPA is imported via large amino acid transporter (LAT). In conclusion, the expression of TH is not sufficient to obtain a DA-producing cell system and this work opened many and answered some questions about DA metabolism