Blood platelets used to be regarded as simple structures with a single purpose in the body – to coagulate blood. We now know that they are multi-purpose structures, from active roles in maintaining the health of our blood vessels, to tissue repair, to maintenance of blood pressure, and ….. to inflammation and immunity.
Platelets are emerging as important players in the abnormal inflammatory/immune processes underlying a wide range of diseases affecting the nervous system (Alzheimer’s, multiple sclerosis, peripheral neuropathy), the liver (non-alcoholic steatohepatitis) and the gut (ulcerative colitis). Abnormal inflammation and immunity are complex, multi-factorial disease processes in which platelets are just one of the players. But increasingly, the platelet is emerging as a major and not a bit player.
Platelets contribute to these diseases by the production of the compound, thromboxane (synthesised within platelets by the enzyme thromboxane synthase). Released by platelets into injured tissue, thromboxane triggers a wide range of inflammatory and immune functions.
Efforts to develop drugs to inhibit excess thromboxane function have come up against two problems. The first is that it has proved difficult to block thromboxane production without blocking the production of other key components of inflammation, leading to unwanted side-effects such as gastric ulceration. The second is that even if a drug could be produced that specifically blocks thromboxane production, there is still the problem of getting it across the blood-brain barrier, something that has proved impenetrable to date.