Levels of Pro-Inflammatory Molecule Could Help Diagnose Primary Sjogren’s Syndrome

Levels of migration inhibitory factor (MIF), a pro-inflammatory immune molecule, are significantly higher in the serum of patients with primary Sjogren’s syndrome, suggesting it could play a part in diagnosing the disease.

MIF levels, however, do not correlate with any clinical characteristics and additional studies are needed to understand its role in the disease.

The study, “Serum and Urinary Macrophage Migration Inhibitory Factor (MIF) in Primary Sjogren’s Syndrome,” was published in the journal Joint Bone Spine.

Primary Sjögren’s syndrome (pSS), a chronic autoimmune disease, affects the body’s moisture-producing glands, leading to symptoms of dry mouth and dry eyes, among other issues.

Immune molecules that work to promote inflammation — called pro-inflammatory cytokines — have been shown to play a key role in several autoimmune diseases.

In particular, the pro-inflammatory cytokine MIF has been shown to play a role in systemic lupus erythematosus and rheumatoid arthritis.

One study has even shown that levels of MIF in the serum (a protein-rich liquid that separates out when blood coagulates) of patients with pSS are increased compared to healthy individuals.

Researchers set out to investigate the significance of MIF levels in serum, as well as MIF levels in urine, of patients with pSS.

They studied 42 adults with pSS and two separate healthy control groups — one for serum MIF levels and one for urinary MIF levels.

Urinary MIF concentrations were calculated as a urinary MIF/creatinine (a protein normally excreted in urine) ratio to control for urinary dilution. The ratio was designated as uMIF.

Results showed that MIF was detectable in all serum and urinary samples across both pSS patients and healthy controls. However, researchers found no differences between uMIF levels in pSS patients and the healthy controls.

On the other hand, MIF levels in the serum of pSS patients were significantly higher than those of the healthy controls. Statistical analysis revealed that serum MIF levels were more than twice as high in pSS patients compared to healthy controls.

But studies on the relevance of high serum MIF or uMIF levels found no relationship with patient or clinical characteristics. Additionally, uMIF levels did not correlate with serum MIF levels.

One previous study had indicated that patients with certain types of kidney disease tend to have higher levels of urinary MIF. However, only two pSS patients in this cohort exhibited kidney manifestations, which is too low to determine a relationship between the two variables.

Nevertheless, investigators said that “future research examining the potential of uMIF as a biomarker in pSS patients with renal [kidney] involvement would be of value.”

“Future studies in larger, well-characterised cohorts are needed to further understand the potential role of MIF as a biomarker in pSS,” they said.