Trace Element Levels in Patients with Familial Mediterranean Fever Fmf Hastalarında Eser Element Düzeyleri

Objective: Although the genetic etiology of familial Mediterranean fever (FMF) is known, limited information is available regarding the regulation of inflammation during attack-free periods. The aim of this study was to determine the alterations in serum copper (Cu), zinc (Zn) and selenium (Se) levels that may be associated with inflammation during attack-free periods in FMF patients. Materials and Methods: This study included 33 patients with FMF and 30 healthy volunteers. Erythrocyte sedimentation rate (ESR), the serum C-reactive protein (CRP) level and serum levels of Cu, Zn and Se in FMF patients and healthy volunteers were assessed by the atomic absorption spectrophotometry method. Results: ESR and serum CRP levels and serum Cu and Zn levels were similar between patients with FMF during an attack-free period and healthy controls (p>0.05). Serum Se levels in the patient group were significantly higher than in the control group (p<0.05). Conclusion: Our study shows that levels of trace elements in serum are variable in patients with FMF during attack-free periods. Serum Se concentrations may at least in part contribute to the subclinical inflammation in FMF patients during attack-free periods. However, further studies are necessary to confirm this result.nuçları değerlendirmek için yeni çalışmalara ihtiyaç bulunmaktadır.


Introduction
Familial Mediterranean fever (FMF), also known as hereditary polyserositis, is an autosomal recessively-transmitted disease that is principally recognized in certain Mediterranean populations [1].FMF is manifested clinically by periodic episodes of fever with peritonitic abdominal pain, pleuritis, rashes and arthritis and is associated with a severe acute phase response [2].FMF is a chronic inflammatory characterized by a mutation in the FMF gene (MEFV), which maps to chromosome 16p and encodes the pyrin/Marenostrin protein [3,4].MEFV is highly expressed neutrophils [4,5].Pyrin participates in various intracellular signaling pathways to cause overexpression of IL-1beta in neutrophils.Excessive neutrophil activation increases the level of oxygen free radicals, such as the superoxide anion radical and hydroxyl radical, and accordingly induces systemic inflammation, which is implicated in the pathogenesis of several diseases, such as rheumatoid arthritis, ankylosing spondylitis and Behcet's disease [6,7].
FMF is characterized by usually free, short-lived and prolonged inflammation attacks.Colchicine therapy is effective for the prevention of FMF inflammation attacks and results in an attack-free period [4].In recent studies, oxygen free radicals were implicated in the inflammation attacks of FMF [8].Elevated levels of reactive oxygen species (ROS) that play an important role in the inflammatory process can initiate DNA damage and contribute to tissue destruction [9,10].
There are various protective mechanisms against the harmful effects of oxygen free radicals in the human body.Free radicals are controlled by the antioxidant defense system, which includes enzymes such as catalase, superoxide dismutase, glutathione peroxidase and multiple non-enzymatic antioxidants [11].The functions of antioxidant enzymes are linked to anti-inflammatory properties.Copper (Cu), zinc (Zn) and selenium (Se) are necessary trace elements for cellular protection against the harmful effects of ROS.Therefore, trace elements have a protective role against the inflammation as cofactors for antioxidant enzymes.The essential trace element Cu is a micronutrient that plays an important role in different biochemical reactions [12].Zn is involved in numerous metabolic processes, including protein synthesis, immunological function as well as growth and development [13].Se is a component of glutathione peroxidase and iodothyronine-5 deiodinase, and it plays an important role as a cofactor for glutathione peroxidase enzymes [14].
In the present study, we aimed to define the serum levels of trace elements in patients during attack-free periods of FMF and to identify whether trace elements may be an important factor in the inflammation attacks of FMF.

Materials and Methods
This study was conducted at the Nephrology and Physical Medicine and Rehabilitation Outpatients Clinics.The study was approved by the local ethics committee.All participants were informed of the study protocol, and their written informed consent was obtained according to the Declaration of Helsinki.
Thirty-three patients with FMF were consecutively included in the study.The diagnosis of FMF was established according to criteria defined by Livneh et al. [15].All of the patients (15 males, 18 females, mean age 30.54±10.03years, mean disease duration 6.15±5.01years) were in an attack-free period.Attack-free periods were defined as being free of an attack for at least 3 weeks.
All patients with FMF were treated with colchicine at the time of the study (1-1.5 mg/day) and were therefore maintained in an attack-free period.None of the patients took any drugs other than colchicine.The results were compared with 30 age-and sex-matched healthy controls (13 males, 17 females, mean age 30.36±7.82 years).Thirty apparently healthy individ-uals without a history of inflammatory or general disease were selected as the control group.None of the healthy subjects or patients were habitual smokers and/or alcohol drinkers, and all participants were free from liver and kidney diseases, diabetes, peripheral neuropathy, familial hypercholesterolemia, thyroid and parathyroid diseases, hematological, lymphoproliferative and other malignant diseases.
The serum samples were kept at -80°C until biochemical determinations were carried out, and hemolysed samples were excluded.All serum samples were obtained during morning hours to avoid diurnal variations.Serum Cu, Zn and Se levels were determined by atomic absorption spectrophometry (Perkin Elmer, Singapur).
Laboratory parameters included erythrocyte sedimentation rate (ESR) and serum C-reactive protein (CRP).ESR and CRP values were determined in whole blood and serum aliquots, respectively.ESR was determined according to the Westergren method, and CRP levels were determined by a nephelometric method (Beckman Array Protein System, USA).ESR and CRP values were used to determine the intensity of the inflammatory process during an FMF attack-free period.

Statistical analysis
Data were processed using the Statistical Package for the Social Science (SPSS 11.0) program.The findings are expressed as the mean±standard deviation (SD).Differences between groups were performed using the Mann-Whitney U test.A p-value less than 0.05 was considered statistically significant.1.There were no statisti-  1.

Some of the clinical characteristics of the patients and control subjects are shown in Table
ESR and CRP values and serum Cu and Zn levels were similar between the FMF group and healthy control groups (p>0.05).The serum Se levels in the FMF patients in an attackfree period were significantly higher than in the healthy controls (p<0.05).

Discussion
FMF is characterized by recurrent episodes of painful inflammation in the abdomen, chest or joints, and these inflammatory attacks have not yet been clearly explained [16][17][18].One of the factors involved in the inflammatory attacks of FMF is oxidative stress [8].Increased levels of free radicals play an important role in the inflammatory process and contribute to tissue destruction.Antioxidants are the first line of defense against free radical damage.The antioxidant system is divided into two parts, enzymatic and non-enzymatic.Antioxidant enzymes, such as Cu-Zn-superoxide dismutase, paraoxonase, arylesterase and malondialdehyde, and trace elements, such as Cu, Zn and Se, play an important role in the protection of cells and tissues against free radical-mediated tissue damage [19][20][21].Decreases in the levels of trace elements may lead a reduced antioxidant activity.However, our knowledge about the role of trace elements in inflammation attacks associated with FMF is limited.
The primary trace element Cu has an important function as a micro-source in numerous biochemical reactions.Alterations of Cu levels have been reported in previous studies.Cu levels are higher in systemic lupus erythematosus patients than in control groups [22].However, decreased Cu levels have been reported in biopsy results from the mucosa of patients with inflammatory bowel disease [23].Our study is the first to examine trace element levels in FMF patients.Therefore, we cannot compare our results with the same patient group of another study.
Zn plays an important role in various biological activities in the body homeostasis.For example, it is a co-factor for the synthesis of enzymes, such as superoxide dismutase and glutathione peroxidase [24].A study of fibromyalgia patients mentioned significant increases of serum Zn levels.In a study on rheumatoid arthritis and osteoarthritis, there was no statistical difference between control groups for levels of Zn in plasma and synovial fluids.Cu and Zn levels in attack-free patients with FMF are similar to the control group, and there is no statistically significant difference [25][26][27][28].
Based on the ESR and CRP values obtained in the present study, systemic inflammation and activation of the classic complement pathway were not observed in attack-free FMF patients, which differ from previously published reports.
Se is recognized as a major non-enzymatic antioxidant.This essential nonmetallic trace element has an important role in vitamin E metabolism [29].We found a significant difference between serum Se levels in FMF patients and controls.There are various reports in the literature regarding serum Se levels in Behcet's disease that support our study [30].Nevertheless, decreased serum levels in different patient populations have been reported in the literature [28,31,32].Our study shows that increased serum Se levels had a systemic anti-inflammatory effect in attack-free patients with FMF.This effect may be due to the non-enzymatic antioxidant character of Se.Further studies are required to clarify the association between nonenzymatic antioxidant systems, inflammatory pathways and serum Se levels in patients with FMF.

Table 1 . The clinical and laboratory features of patients with FMF and healthy controls
ESR: erythrocyte sedimentation rate, CRP: C-reactive protein, Cu: copper, Zn: zinc, Se: