Diabetic Retinopathy
The diabetic retinopathy is a serious eye disease that can affect those with diabetes, and is one of the Main causes of blindness worldwide in the working-age population.
Although it is now clear that the effects of diabetic retinopathy are mainly due to neurovascular changes affecting the retinastill trying to understand how the hyperglycaemia typically associated with the diabetes can lead to this kind of damage.
Data from new research has shown that mitochondria, structures inside our cells, play an important role in the development of diabetic retinopathy.
Mitochondria and the MQC system
Mitochondria are small organelles present within our cellsand they work a bit like 'power plants'. Their function, in fact, is to produce the energy needed by each cell to power all the processes that take place within it. The number of mitochondria present in a cell depends on the energy requirements of the cell itself, and is strictly regulated by a mechanism called mitochondrial quality control (MQC), Mitochondrial Quality Control). This mechanism is the result of a delicate balance between two phenomena:
- the mitophagyi.e. the elimination of damaged mitochondria;
- the mitochondrial biogenesisi.e. the production of new mitochondria to replace those that have just been eliminated.
When the cell is healthy, this balance is perfectly maintained, and the cell can always count on an adequate number of functioning mitochondria for its energy needs.
Mitochondria and diabetic retinopathy
The MQC system plays an essential role in the functioning of the central nervous system and its decompensation has been associated with some of the degenerative diseases more common, such as Parkinson's or Alzheimer's disease. Also mitochondria are thought to play an important role in the development of diabetic retinopathysince numerous studies have shown the presence of abnormal mitochondria in the retina of subjects suffering from this disease, and a recent study hypothesises that the cause may be associated precisely with an 'abnormal mitochondria'.disturbance in the balance of the MQC system.
According to the study, in fact, the presence of diabetes impairs the MQC of the outer retinal mitochondriawith different effects depending on the stage of advancement of the disease:
- in the first steps of diabetes, hyperglycaemia excessively accelerates the mitophagy processThis leads to the elimination of mitochondria. The biogenesis mechanism thus fails to replace all the eliminated mitochondria, and the cell is left with an insufficient number of mitochondria to meet its energy needs;
- in the more advanced stages of diabetes, on the other hand, mitophagy not only slows down progressively, but becomes inefficient. The cell, in fact, no longer recognises the damaged mitochondria, which accumulate with serious consequences for its health.
According to the research results, the MQC alteration observed in patients with diabetes could be caused by thepremature ageing of the outer retinaalthough its cause remains to be clarified.
The results of this study help shedding light on the mechanisms linking the presence of diabetes to retinal health and which, in some cases, result in the appearance of the diabetic retinopathy. This new knowledge could also lead to the search for new therapies which have the specific objective of rebalancing the MQC system in the early stages from the onset of diabetes, so as to prevent the onset of diabetic retinopathy and associated neurovascular damage.
Source:
Hombrebueno J.R. et al, Uncoupled turnover disrupts mitochondrial quality control in diabetic retinopathy. JCI Insight. 2019; 4(23):129760
Dr. Carmelo Chines
Direttore responsabile
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