Systemic Lupus Erythematosus is a female predominant, auto-immune disease with variable presentations, course and prognosis characterized by remission and flares. Various factors are responsible, one of them being estrogen. There are many complex mechanisms working at genetic level and the exact association of estrogen and the disease activity is still not clear.
Materials and method
A cross-sectional study carried at AMCH, Dibrugarh. 123 subjects satisfying SLICC 2012 criteria were taken up for study. Their SLEDAI score was calculated for disease activity and at the same time, blood samples were taken for estrogen level estimation. Cases were grouped into- follicular, ovulatory & secretory phase. All the males were categorized under a different group. Graphs were plotted between the SLEDAI score and the estrogen levels as a whole and then with each phases of the menstrual cycle. Spearman’s co-relation co-efficient was used.
Male:Female ratio was 1:24 with the mean age of 30.3 ± 6.1 yrs. The ANA blot was positive in 86.9% of cases. A significant positive co-relation (p<0.000) was found between the serum estrogen level and the disease severity in follicular and luteal phase but not in ovulatory phase. But, on calculating the mean value of every group (mild, moderate & severe according to SLEDAI) it was seen that, as the disease activity increased from mild to moderate, the estrogen level also increased but then, there was a downfall in the estrogen level when the disease activity was severe.
Estrogen level has a co-relation with the disease activity in SLE patients in a positive quadrant but once the disease activity is severe, this relation breaks apart and it sways in a negative direction.
Systemic Lupus Erythematosus (SLE) is an auto-immune disease in which organs and cells undergo damage, initially mediated by tissue binding auto-antibody and immune complexes. SLE is a complex disease with variable presentations, course & prognosis characterized by remissions and flares. The varied manifestations may involve the renal, gastrointestinal, cardiovascular, muco-cutaneous, musculoskeletal, pulmonary, ocular, neurological and haematological system of our body. The extreme heterogeneity of the disease has led some investigators to propose that SLE represents a syndrome rather than a single disease.1 The mortality occurring in SLE patients has shown a bimodal peak.2 The early mortalities are related to the disease itself (especially lupus nephritis) and late mortalities are related to cardiovascular complications.3 The first case in India was reported in 1955.4
There are evidences of hormone effect, genes on X chromosome and epigenetic differences between the genders playing a role.5 Supporting to the hormonal factor there are studies showing that women using estrogen containing oral contraceptive pills or hormone replacement therapy have an increased risk of developing SLE. The explanation given is that, estradiol binds to receptors on T and B lymphocytes, increasing activation and survival of those cells, thus favouring prolonged immune responses.6 Genes on the X chromosome that influences SLE such as TREX-1, may play a role in gender differentiation because some genes on second X chromosome are not silent. This is evident as XXY karyotype male have significantly increased risk of SLE.7 There are studies which support the concept that sex hormones modulate the incidence and severity of disease in patients with SLE. It is not just limited to estrogen but also involves testosterone, progesterone, and prolactin.8 The link between female hormone and SLE is further strengthened by the fact that more than 50% of genes whose expressions are altered during the hormone-controlled female menstrual cycle are also altered in SLE women.9 Many studies have focused on the genetic causes of this gender biasness. Most of them focus over the lymphocytic expression. Normally during menstrual cycle there is estrogen-mediated increased expression of TNFRSF14 (Tumor necrosis factor receptor superfamily member) mRNA in PBMCs (Peripheral Blood Mononuclear Cells) but in SLE patients, there is decreased expression of TNFRSF14 mRNA, which results in only partial immune suppression by BTLA (B and T lymphocyte Attenuator) culminating in overall immune enhancement. This TNFRSF14 normally interacts with BTLA and downregulates lymphocyte activation. Physiologically in females this mechanism is altered as compared to males. Surprisingly, the same alteration is seen in SLE patients as compared to controls.10 Another molecular mechanism is the increase in ERα (Estrogen Receptor α) and decrease in ERβ mRNA expression in PBMCs of SLE patients and various studies have reported an ERα-mediated signaling for exaggeration of lupus disease.11
Over the years multiple studies have been conducted across the globe to look at the association of serum estrogen level in patients of SLE. The result of those studies show a variable amount of discrepancies. This showed that there lies a gap in the knowledge and understanding of the association. Considering these facts this study was undertaken with objective to study the estrogen level in SLE patients and to correlate estrogen level with disease activity using SLEDAI (SLE Disease Activity Index) score.
MATERIALS AND METHOD
It was a hospital based cross-sectional study carried out in the department of medicine of Assam Medical College and Hospital, Dibrugarh over a period of 1 year. All the SLE patients (diagnosis was based on 2012 Systemic Lupus International Collaborating Clinic Criteria - SLICC), more than 12 years of age attending the rheumatology OPD or admitted under any department in our college were taken as cases. Patients who were pregnant, taking any oral contraceptive pills or refuse to give consent were excluded from the study. Using the formula N = Z2 x p x (1-p) / CI (CI = 95%) a sample size of 150 was reached. After considering the inclusion and exclusion criteria, a total of 123 cases of SLE were included in the present study. Their routine investigations were done which consisted of complete blood count, liver function test, renal function test, routine urine analysis and ECG. Blood samples were collected for estrogen measurement and at the same time their SLEDAI score was calculated. After this, the cases were divided into 3 groups based on the phase of their menstrual cycle as follicular phase group, ovulatory phase group and secretory phase group. All the males were categorized under a different group. Graphs were plotted between the SLEDAI score and the estrogen levels as a whole and then with each phases of the menstrual cycle. Spearman’s co-relation co-efficient was used and results were put in the form of tables and graph.
Total of 123 cases were selected and M:F was 1:24 with the mean age of 30.3 ± 6.1 yrs. Most common constitutional symptom was malaise (46.3%) followed by fatigue (37.4%) and the most common mucocutaneous feature was hair fall (60.1%) followed by malar rash (37.4%). The ANA blot was positive in 86.9% of cases. The ANA profile revealed various antibodies as shown in Figure 1. The categorization of the cases according to their SLEDAI score and the various phases of menstrual cycle has been shown in Table 1.
|SLEDAI SCORE||FOLLICULAR PHASE||OVULATORY PHASE||LUTEAL PHASE||MALE||TOTAL|
|4 – 12||42||05||25||02||74 (60.1%)|
|TOTAL||60 (48.7%)||11 (8.9%)||48 (39%)||04 (3.2%)||123 (100%)|
The co-relation between estrogen as a whole and SLEDAI score is shown in Figure 2 and the further following graphs show the SLEDAI score co-relation with the various phases of menstrual cycle in Figure 3,4,5.
In figure 3, co-relation was significant at the 0.01 level (2-tailed). So, statistically it was a very significant finding with positive co-relation of +0.662. (p-value 0.000)
In figure 4, as the co-relation is significant at the 0.05 level (2-tailed) so, statistically it was not a very significant finding despite showing a positive co-relation of +0.561. (p-value 0.073)
In figure 5, the co-relation is significant at the 0.01 level (2-tailed) so, statistically it was a significant finding with a positive co-relation of +0.561. (p-value 0.073)
As the total number of cases of male sex were only 4, it was not possible to derive any co-relation between the score and estrogen level. Table 2 shows the estrogen level of patients in various phases of their menstrual cycle with male sex in a separate column.
|ESTROGEN LEVEL (pg/ml)||FOLLICULAR PHASE||OVULATORY PHASE||LUTEAL PHASE||MALE||TOTAL|
|500- 1000||07||01||03||01||12 (9.7%)|
|TOTAL||60 (48.7%)||11 (8.9%)||48 (39%)||04 (3.2%)||123 (100%)|
When the mean estrogen levels were calculated of all the cases belonging to mild disease activity (SLEDAI <4) it came out to be 161.4 ± 8.6 pg/ml, similarly for moderate disease activity group (SLEDAI 4-12) it was 2690 ± 127.4 pg/ml and for severe disease activity group (SLEDAI >12) it was 760.1 ±37.8.
Systemic lupus erythematosus (SLE) is the prototypic autoimmune chronic inflammatory disease. The disease has various flare and remission predominantly occurring in third decade of life with a female preponderance. Many studies have been done with regards to the estrogen level and the disease activity. Studies have shown varied results.
In our study the most common age group suffering from SLE was 30-39 yrs (51%) which was similar to a study done by Balachandran S. Bhat et al.12 The findings of common constitutional symptoms of malaise (46%) and fatigue (37.4%) were similar to study of Metry et al with fatigue found in 35.2% of the cases.13 But there are studies where fatigue accounts for 90% of the cases. In a review article by Concha and Werth hair loss was said to be one of the most common feature of mucocutaneous symptoms, ranging from 14%-50%.14 This literature supported our finding of 60% cases having hair loss. Though in our study malar rash was found in 37% cases, studies done by Mansour et al and Zian et al reported it to range from 68%-96%.15,16 This major difference in the finding could be explained on the racial and ethnic differences of the study population taken in their study and our study. The number of ANA positive patients in our study (86.9%) is in accordance with studies done by Teke et al, Malaviya et al, Sham et al.17,18,19 In our study, patients were categorized into 3 groups according to the SLEDAI score. 8.9% belonged to mild disease activity group, 60.1% belonged to moderate activity and rest 30.8% belonged to severe disease activity group. In a study conducted by Folomeev et al, 11 out 15 patients i.e. 73.3% belonged to severe disease activity group and 4 belonged to moderate disease activity group (26.6%) and none were there in mild disease activity group.20 As the total patients in the study done by Folomeev were only 15 our study could not be co-related well with the study. Further in our study, we also classified the subjects based on their phases of menstrual cycle i.e. follicular, ovulatory, luteal and menopausal phase. On dividing it was found that 48.7% of the study subjects were in the follicular phase of their cycle, 8.9% were in the ovulatory phase, 39% were in the luteal phase. None were in the menopausal phase. The remaining 3.2% were males, categorised into a different group (Table 2). No relevant related study could be found in the literature doing the categorization of the patients as above so comparisons could not be done.
Compiling the above data, it was found that the patients with severe disease activity were mostly in the luteal phase of their cycle i.e. 44.7% (17 out of 38). Those falling in the category of moderate disease activity belonged maximally to follicular phase i.e. 52.7% (42 out of 74) and again those with mild disease activity belonged maximally to luteal phase i.e. 54.5% (6 out of 11).
On comparing the level of estrogen with the SLEDAI score as a whole (Figure 2), we found that with increasing SLEDAI score the estrogen level increases. This was in concordance with the study done by Chen and Li21 were they found that the lupus activity is related to incremental estrogen level. Similarly, the study done by Verthelyi et al22 showed a higher level of estrogen in SLE patients as compared to control. There was a significant co-relation between the estrogen level with SLEDAI score among the patients in the follicular and luteal (co-relation coefficient r = +0.662 and +0.560 respectively and p – value is < 0.000) (figure 3 & 5). But in contrast to the above two results it was seen that, lupus patients belonging to the ovulatory phase of the menstrual cycle despite having a positive co-relation (r = +0.561) it was not found to be statistically significant (p – value 0.073) (figure 4). Similarly, in male group the co-relation could not be established as the number of subjects in this group was very less. No study could be found in the literature for comparison of these phase wise results.
Though the co-relation between SLEDAI and estrogen was found statistically significant with a rising trend, meaning that, higher the disease activity higher was the estrogen level, but on analysing the mean value of every group it was seen that as the disease activity increased from mild to moderate, the estrogen level also increased but then, there was a downfall in the estrogen level when the disease activity was severe i.e. SLEDAI > 12.
This finding could be explained by the hypothesis that elevation of aromatase activity occurs in mild and moderate SLE disease activity but in patients with severe disease activity the aromatase activity decreases significantly. SLE is a chronic illness state which leads to a stress like situation and the patients with severe SLE activity had maximal stress.23 This is expected to alter the hypothalamic control of GnRH (Gonadotrophin releasing hormone) secretion which leads to gonadal dysfunction. Similarly, the studies done by Lavelle et al and Vilarinho had evaluated the hypothalamic-pituitary-gonadal axis using intravenous infusion of lutenizing hormone releasing hormone and β-HCG respectively.24,25 They found that serum estrogen level was lower in SLE patients. Though they did not co-relate it with the disease activity, they supported the fact that the hypothalamic-pituitary-gonadal axis is affected in SLE patients.
In contrast to above findings study done by Miller et al showed that, though the estrogen level in SLE patients is higher, there is no significant relationship between disease activity and serum estrogen level.26
From this study we can conclude that, though estrogen is one of the factors for predominance of SLE in female gender, it’s role is limited till the disease activity is in the moderate range. Looking at the above findings and the literature, it is suggested that we should take into account the hormonal imbalance only in those patients belonging to minimal and moderate disease activity group and exclude those with severe disease activity.
We acknowledge all the patients who helped to make this study possible and also the staff of Radioimmunoassay center for their immense help.
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