The aim of the present study was to evaluate the possibility of making use of the specific activity of N-acetyl-β-hexosaminidase, its isoenzymes and β-glucuronidase--potential indicators of salivary gland damage--in the detection of early onset of salivary gland impairment in RA, which is also demonstrated by xerostomia.
For this purpose RA xerostomic salivary patients (unstimulated salivary flow >0.1 mL/min) were compared with RA xerostomic hyposalivary patients (unstimulated salivary flow ≤0.1 mL/min), RA patients without xerostomia (unstimulated salivary flow >0.1 mL/min) and generally healthy controls (unstimulated salivary flow >0.1 mL/min, without xerostomia). Salivary N-acetyl-β-hexosaminidase, its isoenzymes A and B, and β-glucuronidase specific activity were determined according to the Marciniak et al. method. The protein content in the unstimulated saliva was determined by the bicinchoninic acid method.
In xerostomic rheumatoid arthritis patients, the specific activity of salivary β-glucuronidase and isoenzyme A was significantly higher than in the healthy controls but the specific activity of salivary N-acetyl-β-hexosaminidase, its isoenzyme B and β-glucuronidase was significantly lower than in xerostomic hyposalivary rheumatoid arthritis patients.
We suggest a simple, safe and cheap method for the determination of exoglycosidases as a useful tool for the diagnosis of early stages of salivary gland involvement in rheumatoid arthritis.