Can the Thiol/Disulfide Imbalance Be a Predictor of Colchicine Resistance in Familial Mediterranean Fever?

Familial Mediterranean fever (FMF) is a chronic autoinflammatory condition characterized by fever attacks and recurrent polyserositis. Subclinical inflammation that persists during attack-free periods can result in oxidative stress (OS) damage. Thiol groups bind to reactive oxygen radicals and protect cells and tissues from OS damage. The aim of this study was to investigate the relationship between thiol-disulfide balance and colchicine resistance in FMF patients during an attack or attack-free period. A newly developed spectrophotometric method was used to measure native thiol (NT) and disulfide (DS) levels in FMF patients and an age-sex matched group of healthy controls. NT and DS levels were compared in FMF patients 1) with vs. without colchicine resistance; and 2) during an attack (FMF-AP) vs. attack-free period (FMF-AFP). A total of 118 FMF patients and 60 healthy controls were studied. NT (P < 0.001) and total thiol (TT) (P < 0.001) levels in FMF patients were significantly lower compared to healthy controls. NT (P = 0.030) and TT (P = 0.010) levels of FMF-AP patients were significantly lower than that of FMF-AFP patients. FMF-AP patients had significantly higher DS levels than FMF-AFP patients (P = 0.039). Compared to FMF patients without colchicine resistance, elevated levels of DS (P = 0.019) but not NT (P = 0.620) and TT (P = 0.718) were found in those with colchicine resistance. Thiol-disulfide homeostasis is altered in FMF patients during an attack period and this imbalance may be associated with colchicine resistance.

Decreased Chitotriosidase Activity and Levels in Familial Mediterranean Fever

Different studies have demonstrated changes in chitotriosidase (ChT) activity and concentrations in multiple diseases. However, changes in ChT activity and concentrations have not been concurrently evaluated in patients with Familial Mediterranean Fever (FMF). In this study, we analyzed the changes in serum ChT activity and concentrations in patients with FMF. The study included a total of 80 patients with FMF and 80 healthy controls. ChT enzyme activity and concentrations were measured and then compared between the groups. ChT activity was measured by using fluorometric ELISA and ChT concentrations were measured by using colorimetric ELISA methods. The median ChT activity was 10.00 (6.00–15.00) nmol/mL/hr in the patients and 14.00 (6.25–20.75) nmol/mL/hr in the controls. There was a statistically significant difference in the ChT activity between the controls and patients (P = 0.027). The median ChT concentrations were 65.40 (46.20–84.92) pg/mL and 125.00 (75.72–143.95) pg/mL in the patients and controls, respectively (P < 0.001), which were expressed as median percentiles (25th–75th). Additionally, we found no correlation between C-reactive protein and ChT activity (P = 0.978, r = 0.003) and concentrations (P = 0.446, r = −0.87). Serum ChT enzyme activity and concentrations may not be considered as a biomarker in FMF patients taking colchicine. New studies are needed to evaluate the changes of enzyme activity and concentration in colchicine-negative patients.