Research projects

Project objectives

1. Study of clinical characteristics and description of the autoimmune disease developed spontaneously in mice lacking PSGL-1.
2. Study of the evolution of autoimmune diseases developing in mice lacking PSGL-1 as they age.
3. Study of the contribution of PSGL-1 and its ligands in the development of autoimmune diseases in patients with involvement of the connective tissue (scleroderma), as well as in patients with intestinal inflammatory diseases (colitis ulcerosa, Crohn's disease).

Results

The autoimmune study was undertaken using WT mice lacking PSGL-1 and it was observed that the serum of mice deficient in PSGL-1 presents a complex pattern of auto-antibodies which recognise antigens connected with autoimmune diseases affecting connective tissue (Scl-70, Sm, RNP, Jo-1 and SSA/Ro). At early ages only anti-Scl-70 is detected, while at advanced ages the mice present several circulating antibodies.

A histological study was conducted on skin, skeletal muscle and lung tissues to analyse the involvement of internal organs:

• Thickening of the dermis was observed due to the accumulation of collagen (a crucial characteristic for the diagnosis of scleroderma) at earlier ages (6 weeks), indicating that the disease is totally established at this age.
• It was possible to describe how mice deficient in PSGL-1 from the age of three months present a myopathy which causes muscular weakness, with high levels of CK and GOT in serum. This type of myopathy is very common in patients with scleroderma.
• The mice deficient in PSGL-1 were seen to present renal problems at the age of three months, with almost 40% of glomerules affected. Analysis of the serum in these mice indicates that the levels of creatinin and urea in serum are higher in mice that are deficient in PSGL-1 than is the case in WT mice, while the level of albumin is lower. They also present problems with proteinuria and haematuria after the age of 18 months. The results correspond to serious renal involvement, very common in patients with systemic sclerosis.
• Histological analysis of the lung indicates the presence of interstitial infiltrates of leukocytes in 10% of the mice deficient in PSGL-1 at an early age, while this percentage rises to 60% in mice older than one year, in which it is also possible to observe a point of fibrosis. Interstitial pneumonia is common in patients with scleroderma. These lung lesions, with loss of structure, lead to vascular problems such as arterial hypertension in the lung, which is currently the main cause of death in patients with systemic sclerosis.