Abnormal secretion of a protein plays a role in dry eye

A study from the University of Southern California (USC) Roski Eye Institute could help to better understand the tear secretion in patients with Sjogren’s syndrome. (Cusabio offers protein, enzyme, antibody and gene. http://www.cusabio.com/Recombinant-Protein/Recombinant-mouse-Tryptase-11029971.html)

Sjogren’s syndrome is an auto-immune inflammatory disease in which the immune system attacks glands that secrete fluid. Common symptoms include dry eyes and dry mouth, but it can also affect other organs, such as brain, liver and kidney. Inflammation within the glands reduces fluid production causing painful burning in the eyes, dry mouth, and sometimes dryness in the nasal passages, throat, vagina and skin.

Patients with the disease reported worse mental well-being and more difficulty in identifying feelings than the healthy population. And they also have a higher risk of developing lymphoma. Additional symptoms include severe fatigue, arthritis and memory problems.

It is estimated that up to 4 million Americans suffer from Sjogren’s syndrome. And it affects at least nine times as many women as men. Although this illness is very common throughout the world, its diagnosis and treatment is still extremely difficult. The disease often doesn’t respond to conventional immunosuppressive therapy, and current treatments only manage the symptoms. So there is an urgent need to better understand the progression of the disease.

Previously, the research team showed that the tears of Sjogren’s syndrome patients had different compositions: there are higher levels of cathepsin S. This molecule is known to break down proteins and assist cells in removing waste. Based on this discovery, the researchers assumed that increased cathepsin S levels could be associated with dry eye in Sjogren’s syndrome patients.

To research the secretion of cathepsin S, the team looked at two proteins called Rab3D and Rab27, both of which are linked to the process of tear secretion. The results showed that the tears of the mice that lacked Rab3D contained higher levels of cathepsin S, whereas the mice without Rab27 contained lower levels of cathepsin S.