This article appears on the website of ‘Scienza in rete’: a journal on current affairs and culture, an editorial project of the Zadig Agency shared with the ‘Gruppo 2003 per la ricerca’, an association of highly cited Italian researchers founded to promote scientific culture in Italy.
Even in Italian universities, not only in the National Institutes of Health, it so happens that world-famous experts in apparently unrelated fields work in the same structure on completely different projects. Their paths can thus more easily cross, so that mutual expertise can be enhanced. “This happens only apparently by chance,” explains Paolo Bernardi, Professor of General Pathology at the Department of Biomedical and Experimental Sciences at the University of Padua. “In actual fact, these fortunate coincidences can only occur if you have the foresight to fund important centres: in this way you are sowing seeds on fertile ground, where highly specialised experiences have the opportunity and the desire to compare and enrich each other”.
Paolo Bonaldo, Professor of Cell Biology in the Department of Medical Biotechnology, was studying Collagen VI, a component of the extracellular matrix that he was the first to characterise as a specific form of the protein and not, as previously believed, a product of other forms of Collagen. In those years, when producing transgenic mice was much more difficult than it is today, he had obtained a grant to create a knock-out animal for the Collagen VI gene, with a view to studying all of its functions.
Downstairs in the same building there was Paolo Bernardi, one of the world’s pioneers and leading experts in the study of mitochondria, who at that very time had developed methods to study the functionality of the cell’s energy stations. “Not only that,” adds the Paduan researcher, “in a far-sighted perspective, I had also been funded to study the role of the mitochondria themselves in cell death”.
When the animal model was developed, Bonaldo discovered that the absence of Collagen VI generated a condition attributable to a mild form of muscular dystrophy called Bethlem myopathy. Other researchers at the time were also beginning to hypothesise a link between the deficiency of this substance and this disorder, but there was still no mention of Collagen VI pathologies. It was only in 2002 that another Italian group, led by Enrico Bertini of the Catholic University of the Sacred Heart in Rome, also with the support of Telethon, demonstrated that also Ullrich congenital muscular dystrophy had the same origin and that these pathologies of varying severity depended on different genetic flaws, but had in common that they impaired to varying degrees the production of this specific type of Collagen.
Bonaldo, therefore, without yet knowing that what he had in hand was a model of both these diseases, noticed that the muscle fibres of the animals examined under an electron microscope all had one common feature: abnormal looking mitochondria. What simpler thing to do than to go and ask the expert downstairs if there was any way to assess whether, apart from being structurally abnormal, these organelles were also malfunctioning?
‘That’s how our collaboration began,’ Bernardi explains. “We discovered that the damage depended on alterations in the flow of calcium ions across the membrane of the mitochondria themselves, due to a defect in the function of a channel known as the Permeability Transition Pore (PTP).
The same anomalies were also demonstrated on cultures of myoblasts taken from patients, although, compared to the animal model, the number and characteristics of the mutations involved are much more complex in this case. The defect could be corrected in vitro with cyclosporin A, the same drug used against rejection in transplants, so in record time the Italian researchers were able to start with a pilot study unique in the world on 5 patients of different ages and with different mutations.
It was necessary to ascertain the possible risks associated with the treatment and to try to identify an outcome to assess its possible effectiveness. The most objective data, assessable after a short time, on patients whose clinical condition was already partially compromised, were the histological appearance of the muscle tissue, obtained by comparing two biopsies taken before and after one month of treatment. ‘In fact, after such a short time, the mitochondrial defect was repaired, cell death decreased, and a certain degree of fibre regeneration was also observed,’ says the Paduan researcher.
In view of the positive results, some of the parents of the most severely affected children, plus a couple of others who were later included in the trial, continued the treatment for a longer period of time: ‘After a time span of between one and three years, we measured an increase in the strength of the limbs,’ Bernardi continues, ‘but unfortunately this is not enough to counteract the decline in the patients’ mobility and has no effect on the diaphragm, the most important muscle, because their breathing depends on it. And it is precisely this deficit that is holding back wider experimentation with cyclosporine, which lowers immune defences: combined with poor respiratory function, the drug is in danger of causing serious or fatal bronchopulmonary complications”.
‘This is why we are trying to consider other drugs such as cyclophilin inhibitors, which act on enzymes inside the mitochondrion without interfering with immunity,’ the researcher adds.
A new glimmer of hope appeared last year with a new line of research conducted by Luciano Merlini, of the University of Ferrara, once again thanks to Telethon’s support and again departing from a discovery by Bonaldo: the observation that in the muscles of those suffering from Collagen VI pathologies, in addition to the impaired function of the mitochondria, the control mechanism of autophagy is also compromised. This process, which normally removes and digests damaged organelles, also intervenes to feed the cell with some of its own components when nutrients from outside are lacking.
“It is a phenomenon that is at the centre of attention of many research groups at the moment,” comments Bernardi, “because, beyond these rare diseases, it is involved in the genesis of neurodegenerative, cardiovascular and neoplastic diseases: a further example of how valuable data can emerge from the study of rare diseases, even with regard to conditions of major social impact.
In the animal model of Collagen VI disorders, the defect in autophagy results in the accumulation of impaired organelles, which drive the cell towards apoptosis, thus leading to muscle atrophy. Paolo Grumati, also from the University of Padua, and Luisa Coletto, from the Veneto Institute of Molecular Medicine, demonstrated in Nature Medicine that prolonged fasting or a special low-protein diet, as well as certain drugs, including rapamycin and cyclosporine itself, can restore autophagy and save tissues.
‘It is still too early to talk about an effective cure,’ Bernardi points out, ‘but each new mechanism that comes to light offers new therapeutic perspectives. That is why, as I always say, there is no such thing as an incurable disease: by studying them in depth, you can always find their weak point’.