AbstractBackground and Objective:Systemic lupus erythematosus (SLE) is an autoimmune disease with various organsbeing involved.
Vitamin D is an essential ingredient in regulating the immunesystem. This study aimed to investigate the relationship between vitamin D andthe severity of lupus activity.Materialsand Method: This case-control study wascarried out on 38 patients with lupus on the basis of the ACR criteria and 44healthy subjects with no history of rheumatology disease. Tomeasure the level of 25-hydroxy vitamin D, venous blood samples (5 cc) weretaken from each participant. The activity of the lupus disease was measured bySLEDAI scale.
Chi-square, independent sample t-test, one-way ANOVA and multiplelinear regression analysis were used to measure multivariate effects. The levelof significance was set to be P <0.05.
Results: Thirty-fivelupus patients and 40 healthy subjects were female (P = 0.847). The vitamin Ddeficiency was observed in the case group (42.1%) and control group (11.4%).The mean value of serum vitamin D3 level was 35.3 ng/ml in the controlgroup, 24.
6 ng/ml and 21.3 ng/ml in patients with mild and severe SLE, respectively(P = 0.024).Conclusion: In thisstudy, high levels of 25-hydroxy vitamin D were observed among the healthysubjects, compared to the patients with SLE. Also, the level of vitamin Dsignificantly decreased with increasing severity of SLE activity.
Key words:Systemic lupus erythematosus, Vitamin D, 25-hydroxy vitamin D, SLE activity IntroductionSystemic lupus erythematosus (SLE) is a systemic autoimmune diseasewith various organs being involved. It has different clinical manifestationsfrom a skin and simpledermatologic and joint signs tolife-threatening disorders such as renal, cardiovascular and neurologicalcomplications. The most important manifestation of this disease is renalinvolvement or lupus nephritis, reported in many patients (40-50%). The diseaseoccurs throughout the world; however, its prevalence and severity varies indifferent societies. Over the past 50 years, the incidence of SLE has increasedup to 10 times(1, 2). There is no definite cure for the disease and it is generallyinhibited by corticosteroids and immunosuppressive drugs(2).
Various factors including genetic background, environmentalfactors, gender, hormonal factors and viral infections contribute to theincidence and exacerbation of the disease. Recent studies have indicated therole of vitamin D deficiency in the development of autoimmune and malignantdiseases(2). It should be noted that the individual with SLE are recommendedto avoid sunlight in order for skin rash and disease exacerbation to beprevented, which reduces the serum concentration of vitamin D in these persons(3). Cholecalciferol ismade from 7-dehydrocholesterol by UV rays in skin.
Some foods like egg yolk and fish oil are sources of vitamin D3(4). The level of vitamin D in the body is associated with the season,with its lowest levels observed in winter and its highest levels reported atthe end of the summer(5). Vitamin D is effective in regulating calcium absorption throughendocrine mechanisms and in expressing gens through autocrine mechanisms(6). Vitamin D deficiency is also associated with high risk of ricketsin children and osteomalacia in adults as well as bone fracture, cancer,autoimmune diseases, Infectious diseases, diabetes type I and II, hypertension,heart disease and multiple sclerosis(7). Some studies have shown that the increased vitamin D3concentration enhances telomere length in leukocytes, resulting in longerlifespan of leukocytes and preventing inflammatory disease(8). Vitamin D metabolites and vitamin D receptors exist in a variety ofcells, including immune system cells containing antigen-presenting cells, Tlymphocyte cells, B lymphocyte cells and monocytes. Recent studies have shownthe direct effects of calcitriol on the homeostasis of B cells, such as theinhibition of memory and plasma cells production and an increase in theapoptosis of antibody-producing B cells. Such a cellular immune control is ofparamount importance in autoimmune diseases(5).
Various studies have reported low levels of vitamin D in SLEpatients compared to non-SLE patients(9, 10). A study also claimed a reduction in vitamin D as a risk factorfor SLE patients and found that its enhanced reception prevents SLE andrheumatoid arthritis(11, 12). In some studies, there was a reverse relationship between serumvitamin D3 levels and SLE activity (11, 13, 14). On the other hand in some studies, the vitamin D deficiency was notassociated with the duration of the disease and its severity(2, 3). Because of limited studies and inconsistent findings on therelationship between serum vitamin D levels and the SLE activity and since thisdisease causes a lot of complications for the patient, the current study was todetermine the relationship between vitamin D level and SLE activity. If such arelationship is proved, treatment with vitamin D is much easier than treatmentwith immunosuppressive drugs. Materials and MethodDesign: This case-control study was carried out on 38 patients withSLE on the basis of the ACR criteria and 44 healthy subjects with no history ofrheumatologic diseases. The participants in the control group were referring fromthe Internal Medicine Clinics, had no diagnosed rheumatologic and autoimmunediseases, receive no vitamin D supplementation and were at the pre-menopausalage.
Data collection method: All participants were included in the studyafter being evaluated clinically and laboratory and receiving sufficientdescription by the physician and having informed consent, Venous blood samples(5 cc) were taken and sent to a laboratory in order for their 25-hydroxyvitamin D level and serum creatinine to be measured. 25-hydroxy vitamin D wasmeasured by Corgeh Mix kit (made in Germany) through using ELISA method. D3levels above 30 ng/ml, 30-16 ng/ml and below 15 ng/ml wereconsidered as normal, insufficiency and deficiency(15, 16). The creatinine level was measured with Pars Azmoon kit (made inIran) through using biochemical method. The activity of SLE was calculatedusing the standard SLEDAI instrument, based on clinical and laboratoryfindings. Regarding this scale, the scores below 6, 6-12 and above 12 were alsoconsidered as inactive, mild and severe diseases, respectively.
Data analysis: First, Kolmogorov-Smirnov test was employed to testthe normality of vitamin D3 and blood creatinine data. Then, the mean andstandard deviation of these indices were calculated and independent t- test wasrun. Chi-square and Fisher’s exact tests were used to examine the relationshipbetween qualitative variables. Multiple linear regression analysis were used tomeasure multivariate effects Results This study was performed on38 patients with SLE as the case group and 44 healthy subjects as the controlgroup. Three subjects (9.1%) in the control group and 3 cases (7.9%) in the SLEgroup were male (P = 0.
847). The mean ages of the participants in the controland case group were 34.9 ± 15.9 and 35.7 ± 11.
9 years, respectively (p=0.787).The mean serum creatinine level was 0.93 in the case group and 0.85 in thecontrol group (P = 0.013). The subjects inthe case group had vitamin D3 deficiency (42.1%) and vitamin D3 insufficiency(28.
9%). The corresponding values in the control group were 11.4% and 47.7%,respectively (P = 0.006) (Table 1).The most common clinical signs were as follows: Arthralgia (36.8%),arthritis (31.
6%), photosensitivity (31.6%), anemia (71.1%) and edema (23.7%).Moreover, the most common paraclinical findings were AntidsDNA (84.3%), ANA(81.4%), complement deficiency, positive antiphospholipid and high ESR (18.
4%)(Figure 1).In patients with severe and mild SLE, vitamin D3 deficiency wasobserved in 46.7% and 39.
1% of patients, respectively. There was astatistically significant relationship between the severity of the disease andthe vitamin D3 level (P = 0.026). The mean serum vitamin D3 level was 35.
3 ng/mlin the control group, 24.6 and 21.3 ng/ml in patients with mild and severeSLE respectively. Also, there was a significant difference between these groupsregarding the vitamin D3 level (P = 0.024) (Table 2).Additionally, multiple linear regression analysis was used formultivariate analysis. The results of this model reflected the significanteffects of the disease on the vitamin D level, indicating that the severity ofthe disease enhances as the vitamin D level decreases (B = -7.019).
This modelhad a relatively high explanatory power (Adjusted R Square= 0.64) (Table 3). DiscussionIn this study, serum vitamin D3 level and the disease activity were compared in 38 patients with SLEand 44 healthy individuals. The vitamin D3 deficiency was diagnosed in 42.1% ofpatients and 11.4% of healthy subjects (P = 0.006).
The mean serum vitamin D3level was 23.3 ng/ml for the patients and 35.3 ng/ml for thehealthy group. Although these values were 24.6 ng/ml and 21.3 ng/mlin patients with mild and severe SLE.
Significant difference was observedbetween the groups regarding the vitamin D3 level (P = 0.024), showing asignificant relationship between vitamin D3 level and SLE activity. Inaddition, there was no relationship between vitamin D deficiency and the levelsof albumin, Creatinin, hemoglobin, AntidsDNA titer and complements level (C3, C4, CH50) (P >0.
05),Photosensitivity was also reported in 31.6% of patients.Some studies supported the relationship between vitamin D3deficiency and SLE. Toloza et al. (2010) conducted a study on patients with SLEand found a correlation between vitamin D deficiency and clinicalmanifestations and SLE disease activity(3). In the present study, the high prevalence of vitamin D deficiencyin patients (42.
1%) and its low prevalence in healthy subjects (11.4%) canhighlight the role of vitamin D3 in the pathogenesis and severity of SLEdisease. In Toloza’s et al. study, vitamin D3 deficiency and insufficiency werereported in 17.9% and 66.7% of patients(3).
In Anna Abou-raya’s (2013) study, the mean vitamin D level was19.8 ng/ml among the patients and 28.7 ng/ml in the control group(12). Ruiz -Irastorza et al. (2008) examined 92 SLE patients, of whom75% had vitamin D3 deficiency and 15% had vitamin D3 insufficiency.
Photosensitivity was also observed in 68% of the patients(17).The prevalence of vitamin D3 deficiency in the Ruiz–Irastorza’s etal. study was greater than that in this study.
This can be due to the highphotosensitivity reported in the present study. Reduced photosensitivity canprovide more exposure to sunlight and reduce the likelihood of vitamin D3deficiency(2). Szodoray et al. (2011) conducted their study on 177 patients with SLE andfound that the mean vitamin D3 level was 13.2±6.
28 ng/ml. The prevalenceof vitamin D3 insufficiency and deficiency was observed in 44.6% and 37.
3% ofthe patients(18). These findings are consistent with the findings of the presentstudy. In a systematic review (2013), the relationship between vitamin D3deficiency and SLE was highlighted and sufficient evidence was presented tosupport the correlation between vitamin D3 and SLE; however, the relationshipbetween vitamin D3 deficiency and other clinical features of the disease shouldbe concerned in future studies(19). There are some inconsistencies regarding the findings of somestudies conducted to determine the relationship between vitamin D3 level andthe SLE activity.
For example, Bonakdar et al. (2011) observed a significantrelationship between vitamin D3 deficiency and SLE activity at the onset of thedisease and a more severe vitamin D3 deficiency with low albumin and hemoglobinlevels and a higher Antids DNA titer(20). In Kim’s et al. (2010) study, there was no association betweenserum vitamin D3 level and disease activity with respect to the SLE DiseaseActivity Index and Antids DNA level, even though, a positive correlation wasfound between the vitamin D3 level and hemoglobin and complement(21). Ruiz-Irastorza et al. (2008) noticed no significant relationshipbetween the vitamin D3 level and the severity of SLE but a significantcorrelation between vitamin D3 deficiency and fatigue(17).Furthermore, the present study examined the effects of disease severity onvitamin D3 level by eliminating the effect of confounder factors using multiplelinear regression models. The only factor affecting the vitamin D3 level inthis model was the severity of SLE activity.
In other words, it can beconcluded that decrease in vitamin D3 level leads to an increase in the diseaseseverity. Differences in the vitamin D3 level for the SLE and healthy groupscan be the result of the high prevalence of photosensitivity in SLE patients,high use of sunscreen and the consumption of steroid for the treatment andcontrol of the disease. In Iran and other Islamic countries, women’s veils alsoreduce the skin exposure to sunlight, leading to higher prevalence of vitamin D3deficiency.
In order to reveal the true association between vitamin D3deficiency and SLE disease, studies with a larger sample size and samplehomogeneity in terms of age and gender are recommended. Of subjects, 11.4% experienced vitamin D3 deficiency and 47.7% hadvitamin D3 insufficiency however, these values were 39.1% and 34.
8% in patientswith mild activity and 46.7% and 20% in patients with severe activity,respectively. The findings implied an increased percentage of vitamin D3deficiency as the disease activity enhances (p = 0.026). In CCMOK’s (2017)study on 376 SLE patients, the 25-hydroxy vitamin D level was below 15 ng/mlin 26%, 15-30 ng/ml in 54% and above 30 ng/ml in 20% of thepatients and the vitamin D3 deficiency was associated with disease severity andits tendency to relapse(22).
Cutolo (2009) measured serum vitamin D3 levels in 21 patientswith SLE activity were also assessed using ECLAM and SLEDAI. The results showedthat serum vitamin D3 level in SLE patients was lower than that in the healthygroup and the severity of SLE was inversely correlated with serum vitamin D3level(11). In a cohort study by Amital (2010), 378 patients with SLE wereselected and the disease activity was measured using ECLAM and SLEDAI and serum25-hydroxy vitamin D concentration was also measured in these patients. Thefindings revealed a reverse relationship between serum vitamin D3 concentrationand SLE activity(13). ConclusionIn this study, high levels of 25-hydroxy vitamin D were observed inhealthy subjects compared to patients with SLE and the vitamin D3 levelsignificantly decreased with a significant increase in the SLE activity.AcknowledgementsThis research was based on the results of a research project (No.
90101) approved at Kashan University of Medical Sciences. The authors wouldlike to express their gratitude to all patients who participated in this study. Tables and FiguresTable 1: Frequency, mean and standard deviation of demographic andclinical characteristics of the two study groups variables groups P.
value case control (f/m) sex 35/3 40/4 N.S Age 35.7±11.9 34.
9±15.9 0.787 Creatinin 0.93±0.16 0.85±0.
13 0.013 VitD3 Deficiency 16(42.1) 5(11.4) 0.
006 Insufficiency 11(28.9) 21(47.7) normal 11(28.9) 18(40.9) mean±SD 23.3±15.8 35.3±22.
4 0.007 Severity of SLE Mild 23(60.5) – – moderate 15(39.5) – – mean±SD 1.39±0.49 – – Disease duration 4.08±4.
7 Table 2: Distributiontable of vitamin D serum level with severity of lupus Vit D3 level Severity of disease mean±SD total sufficient insufficient deficiency 35.3±22.4 44 18(40.9) 21(47.7) 5(11.
4) Healthy group(control) 24.6±16.4 23 6(26.
1) 8(34.8) 9(39.1) mild Severity of SLE 21.
3±15.1 15 5(33.3) 3(20) 7(46.7) severe 23.3±15.8 38 11(28.9) 11(28.
9) 16(42.1) case P2=0.024 P1=0.026 P.value Figure1: Clinical sign and symptoms of lupus patients Table3) Regression parameters in estimation of Vit D level based on predictors variables Unstandardized Coefficients t Sig.
Adjusted R Square B Std. Error (Constant) 49.757 14.608 3.406 .001 0.64 Gender -6.037 7.818 -.772 .442 AGE .042 .156 .267 .790 Creatinin level -18.519 15.274 -1.213 .229 SLE Activity -7.019 2.891 -2.428 .018