Neurodegenerative diseases such as Parkinson’s, Alzheimer’s, and multiple sclerosis are disorders that mostly affect the neurons located in the brain. These diseases are incurable, resulting in the death of nerve cells.
About Multiple Sclerosis (MS)
MS cases have increased worldwide. MS is an immune-associated disease characterized by damage and inflammation of the myelin sheath in the spinal cord and brain (demyelination).
The origin of MS is not clear, but it is known that it develops early in life. A majority of MS patients will eventually become disabled, as no treatment is available to effectively address symptoms.
According to an article in the journal MDPI, there is a relationship between human endogenous (deep tissue) retroviruses and events leading to multiple sclerosis. Viral triggers of MS are included in exogenous factors.
Two endogenous retroviruses from the HERV-W group are suspected triggers of MS. The two retroviruses are ERVWE1 and MSRV. Note that expression of the HERV-W retrovirus was discovered in all MS patients’ brain tissue that was studied during the early stages of demyelination and also studied during the late stages of progression.
As to an established cause or mechanism of endogenous retroviruses activation, that is still unclear.
Twenty-five Million Years Ago
In early 1970, scientists discovered endogenous retroviral elements that were acquired by our ancestors over twenty-five million years ago. They are present in the genome which constitutes the complete set of genetic material.
These retroviruses can be traced back to our ancestors’ DNA millions of years ago. Their relationship to the origin of certain diseases, including the study of neurodegenerative diseases, has been well documented.
Among these studies, there is a clear connection between a patient’s health and the expression of endogenous retroviruses. Bacterial infections are also possible factors of MS.
Risk Factors Associated With MS
Immune auto-aggression, sex, age, hormone levels, and Vitamin D deficiency are among the many risk factors that are thought to contribute to a risk of MS.
- Immune Auto-Aggression: cytotoxic T-lymphocytes are associated with erosion of the myelin sheath protecting nerve fibers. This is called demyelination.
- Sex, age, hormone levels: MS is diagnosed most often in females (primarily young females). Whereas late onset of MS neurological events is generally discovered in older females who have gone through pregnancy as opposed to those who did not. The theory is that hormones are associated with a decrease in relapses throughout pregnancy but re-occur post-delivery.
- Vitamin D Deficiency: A vitamin D Deficiency is another potential risk factor of MS. Researchers have established a connection between a decrease in the level of ultraviolet radiation, an increased risk of MS, and a risk of relapse.
A further confirmation involves the vitamin D receptor’s binding to genes implicated in the risk of MS.
As aforementioned, the factors leading to the activation of endogenous retroviruses are unknown. Also, the cause of the increased expression of HERV-W genes in multiple sclerosis remains unclear.
In addition, this applies to retroviral elements in the development of MS. Therefore, further studies in this respect are urgently required.