New paper below [1].
The thymus has an important immunological role during childhood, but strangely, shrivels up at puberty. A PubMed search of gives 1,753 hits, going back 100 years.
Many years ago, I discovered that castration could cause the thymus to regenerate. I wondered what that meant for PCa patients. There didn't seem to be any interest in the literature.
For those who like sweetbreads (as I do), you will be eating the thymus gland.
Why does the thymus involute at puberty? Is there a downside to having a high immunological response? An increased risk of an autoimmune disease?
At the beginning of the covid onslaught, I wondered if it might be beneficial to have a restored thymus.
From Wiki [2]:
"The thymus is a specialized primary lymphoid organ of the immune system. Within the thymus, thymus celllymphocytes or T cells mature. T cells are critical to the adaptive immune system, where the body adapts to specific foreign invaders. The thymus is located in the upper front part of the chest, in the anterior superior mediastinum, behind the sternum, and in front of the heart. It is made up of two lobes, each consisting of a central medulla and an outer cortex, surrounded by a capsule.
"The thymus is made up of immature T cells called thymocytes, as well as lining cells called epithelial cellswhich help the thymocytes develop. T cells that successfully develop react appropriately with MHC immune receptors of the body (called positive selection) and not against proteins of the body (called negative selection). The thymus is largest and most active during the neonatal and pre-adolescent periods. By the early teens, the thymus begins to decrease in size and activity and the tissue of the thymus is gradually replaced by fatty tissue. Nevertheless, some T cell development continues throughout adult life."
From the paper:
"Restored Thymic Output after Androgen Blockade Participates in Antitumor Immunity""The thymus is a hormone-sensitive organ, which involutes with age in response to production of sex steroids. Thymic involution leads to a decrease in the generation of recent thymic emigrants (RTEs), resulting in a reduced response to immune challenges such as cancer. Interestingly, the standard of care for prostate cancer patients is androgen deprivation therapy (ADT), which leads to thymic regeneration and an increase in thymic output. It remains unknown whether these newly produced T cells can contribute to the antitumor immune response. This study defines the kinetics of thymic regeneration in response to ADT in mice, determining that thymic epithelial cell proliferation is critical for the increase in RTE output. Using a mouse model to track RTE in vivo, we demonstrate that these newly generated RTEs can traffic to tumors, where they become activated and produce effector cytokines at levels similar to more mature T cells. Collectively, these data suggest that RTEs produced from ADT-induced thymic regeneration could be harnessed for the antitumor immune response."
-Patrick
