What are Osps?
They are Pam3Cys
The blebs that are shed by borrelia to evade the immune system are covered in Outer Surface Proteins, or Osps, such as OspA, OspB, OspC, and so on. These Osps are characterized by their chemical structure as "triacyl lipoproteins". In organic chemistry, structure equals function. Here we will explain how the Osps function to cause disease.
See the illustration below which shows the chemical structure consisting of three acyl groups on one end of the molecule. The chemical name is "Tripalmitoyl cysteine", abbreviated as Pam3cys, or sometimes P3C. It's easy to see the three acyl groups: the three zigzag lines that are labeled in red. These acyl groups are fatty acids and are what make OspA and other borrelial Osps immunogenic and also damaging to the immune system.
Pam3Cys is a toxin
Triacyl lipoproteins are managed by toll-like receptors 2 and 1, together (TLR2/1), in the human immune system. The TLR2/1 "heterodimer" also manages antigens associated with fungi and lipoproteins from other microbes such as E. coli, tuberculosis and MRSA, to name a few. Triacyl lipoproteins are used in laboratories to induce experimental sepsis. Fungal antigens are known to cause severe neurologic disease.
In 1998 a synthetic OspA product was approved for use as a vaccine known as LYMErix. It was pulled from the market after three years due to numerous reports of severe adverse events, which is not surprising considering the damage a triacyl lipoprotein is capable of doing. For starters, it can damage the brain.
OspA (Pam3Cys) causes brain inflammation
Mario Philipp of Tulane University reported that OspA causes astrogliosis: pathological changes that take place in the brain as a result of damage or disease. Robert Martin & Adriana Marques of the National Institute of Autoimmune and Infectious Diseases (NIAID) reported that OspA causes brain inflammation while humoral immunity is blunted:
"These results show that signaling through TLR1/2 in response to B. burgdorferi can elicit opposite immunoregulatory effects in blood and in brain immune cells, which could play a role in the different susceptibility of these compartments to infection."
There is abundant research describing mechanisms of immunosuppression by Borreliae and their lipoproteins. Click to the next page to learn more.