6. CONCLUSION
T cells ability to mediate the immune response makes them a valuable tool in treating conditions where the immune system plays a crucial role. With advances in medical research and technology, techniques have been developed to modulate T cell activity, offering new therapeutic strategies for many medical conditions. The traditional belief that the CNS is immune-isolated has been challenged by recent evidence of the presence of immune cells within the CNS in both normal and pathological conditions. T cells are demonstrated to enter the CNS through the lymphatic vasculature and the fenestrated capillaries within the CP and populate the dura mater and the CSF. Further understanding of T cells in the CNS and the molecular processes behind these changes in normal conditions can open up new avenues of research in autoimmune diseases like MS, caused by T cells targeting myelin. The presence of T cells also may play a role in AD and PD, with APOE as a key factor in AD and T cell modulation as a potential treatment strategy in PD. The BBB regulates the traffic of immune cells into the CNS, but pathological conditions like MS and stroke can disrupt it. There are various therapies that target T cells to reduce symptoms of MS such as Natalizumab, Fingolimod, and others, while regulation of T cell-mediated response is being explored in AD and Tregs in PD. T cells may also serve as early biomarkers in PD.
However, T cells are not just crucial in pathological conditions, they also play a fundamental role in aging. The aging process leads to a decline in cellular and molecular function, resulting in chronic diseases and increased risk of ARDs. Chronic inflammation, also known as ”inflammaging”, is a hallmark of aging linked to cognitive decline and pathology. T cells are affected by aging and the accumulation of senescent T cells leads to pro-inflammatory cytokine release. This age-related systemic inflammation is connected to impaired cognitive function. Despite this field is an active field of research, more information is needed to fully understand the impact of T cell aging on cognitive decline.