Serum Angiotensin converting enzyme in pemphigus vulgaris.

BACKGROUND: Pemphigus vulgaris is an autoimmune blistering skin disease with unknown etiology. Drugs such as angiotensin-converting enzyme (ACE) inhibitors may contribute in the pathogenesis of pemphigus.
OBJECTIVE: We plan this essay to evaluate the serum ACE level in pemphigus vulgaris patients in comparison with healthy controls to recognize its possible role in disease pathogenesis or activity.
METHODS: This study was planned and performed in the dermatology clinics of Shahid Beheshti University of MedicalSciences' Hospitals between July 2010 and June 2011. Patients with new onset of pemphigus vulgaris were enrolled in our study. Control subjects were frequency-matched to cases by sex and age. Serum ACE was determined by the spectrophotometric method.
RESULTS: Thirty-four patients with pemphigus vulgaris and 35 healthy individuals were recruited in the study. No statistical significant difference was detected in the mean level of serum ACE of the two groups (t-test, P = 0.11). The mean ACE level was significantly lower in male patients compared with male controls (P = 0.04). Moreover, a significant higher serum ACE level of patients with cutaneous involvement was observed compared to patients with mucosal involvement (P = 0.02).
CONCLUSIONS: Despite lack of any significant difference of serum ACE level between pemphigus and control group, the serum ACE level was considerably lower in male pemphigus vulgaris patients compared with male controls. Therefore, ACE might have some association with pemphigus vulgaris especially in male patients; however, further studies are required to confirm this association.

What was known?

Angiotensin-converting enzyme (ACE) inhibitors are one of the causes of drug-related pemphigus.

We hypothesized that ACE could play some role in the pathogenesis of pemphigus vulgaris or disease activity.

To date, there has been no study on the case of pemphigus and the role of ACE in its pathogenesis.

Introduction

Pemphigus vulgaris is a chronic blistering skin disease in which autoantibodies are directed against the cell surface of keratinocytes. The loss of cell-cell adhesion of keratinocytes occur through a process called acantholysis. The majority of patients with pemphigus vulgaris develop the disease spontaneously; however, in a small group of patients, pemphigus occurred after treatment with certain medications such as angiotensin converting enzyme (ACE) inhibitors.[12]

The serum levels of ACE are elevated in sarcoidosis and it is a good marker to monitor disease activity.[3] Moreover, several studies have evaluated the ACE level in skin diseases such as psoriasis and lichen planus,[45] however, there is no data about the assessment of serum ACE level in pemphigus vulgaris. ACE inhibitors are one of the causative agents of drug-induced pemphigus. Therefore, we hypothesized that serum ACE level might alter in patients with pemphigus vulgaris, and ACE could play some role in the pathogenesis of pemphigus vulgaris. Consequently, the aim of this study was to evaluate the serum ACE level in patients with pemphigus vulgaris compared with healthy controls. To the best of our knowledge, this essay seems to be the first study to evaluate the possible role of ACE in the pathogenesis of pemphigus vulgaris and it might be helpful to assess that we could use ACE as a serologic marker for disease activity in pemphigus patients.

Methods

This study was planned and performed in the dermatology clinics of Shahid Beheshti University of Medical Sciences’ Hospitals between July 2010 and June 2011. Consent was obtained voluntarily from each patient at the time of enrollment. The study protocol was approved by the ethics committee of our institution.

Thirty-four new patients of pemphigus vulgaris older than 20 years old, referred to our dermatology clinics, were enrolled in our study. The diagnosis of pemphigus vulgaris was made by a specified dermatologist and confirmed by histopathology and direct immunofluorescence evaluation. Patients with the history of diabetes, hypertension, hyperthyroidism, and sarcoidosis and those with a positive history for ACE inhibitors consumption was excluded.[6]

All the cases participating in our study had negative history for intake of corticosteroids. In addition, persons in the control group who were treated by systemic corticosteroids, at least 4 weeks before the study, were excluded from our study. We enrolled 35 healthy subjects for our control group, who whose age and sex were frequency-matched with our cases. Our control group comprised the clinics’ staff with negative past medical history. The exclusion criteria for the control group were the same as the patient group.

For evaluating the serum ACE level, 10 cc venous blood of each participant was drawn from the cubital vein. The coagulated blood samples were centrifuged to collect the serum. Then, the sera were frozen at –20°C. After gathering all the samples, we referred them to our special laboratory to measure the ACE level. Serum ACE was determined by the spectrophotometric method using furyl-acrylic-phenyl-alanyl-glycyl glycine as the reagent. There are different methods of analyzing ACE level and activity in plasma with no gold standard method.[7] Therefore, we selected furyl-acrylic-pheny-lalanyl-glycyl glycine according to the available facilities in our center. The normal reference range of ACE for the laboratory was 8-65 units for more than 14 years of age.

For all patients, questionnaires requesting information about the sites of involvement by pemphigus vulgaris, duration of the disease, family history of pemphigus vulgaris and other autoimmune diseases, past medical history, and the history of their medications particularly ACE inhibitors and corticosteroids were filled by the physician. In addition, pemphigus area and activity score (PAAS) was used to score the severity of the disease.[8] PAAS is an integer scale that is the sum of mucous membrane and cutaneous score.

Results were expressed as mean ± standard deviation. Independent samples’ t-test was applied to compare the means of continuous variables. When the assumptions of applying t-test for comparing groups were not satisfied, the non-parametric Mann–Whitney U-test was used. Spearman correlation test was used to detect the linear relationship between variables. Statistical analysis was performed using the statistical software SPSS 16.0.0. (SPSS Inc. Chicago, IL, USA). P values less than 0.05 were considered significant.

Results

Thirty-four patients with pemphigus vulgaris (19 women and 15 men, 55.88% vs. 44.12%) and 35 healthy individuals (20 women and 15 men, 57.14% vs. 42.86%) were recruited in the study. Control subjects were frequency-matched to cases by sex and age. The mean ages of patients and control subjects were 44.23 ± 13.37 and 44.35 ± 13.95, respectively. The median duration of the disease was 4.5 months (11.71 ± 23.97 months) with a range of 0.25-108.0 months and two patients had a positive family history of pemphigus vulgaris. In 18 patients (52.94%), pemphigus affected both mucous membranes and the skin, in 10 patients (29.41%), there were only mucous membrane involvement, and in six patients (17.65%) only the skin was affected. Among 28 patients with mucosal and mucocutaneous pemphigus, lesions were observed in the oral mucosa in 28 (100%), nasal mucosa in 2 (7.1%), genital mucosa in 1 (3.6%), and conjunctiva mucosa in 3 (10.7%) patients. Table 1 shows the clinical assessment of severity and progression of pemphigus vulgaris in patients’ group based on Physician's global assessment and PAAS.

Table 1

Clinical severity assessment of patients with pemphigus vulgaris

The mean serum ACE levels in patient and control groups were 25.34 ± 14.25 and 31.97 ± 19.44, respectively. No statistical significant difference was detected in the mean level of serum ACE of the two groups (t-test, P = 0.11). In this study, the mean serum ACE level was 26.00 ± 14.23 in female controls and 39.93 ± 22.90 in male controls, with a statistically significant difference (t-test, P = 0.03). However, no significant difference was observed in the mean level of serum ACE of female and male cases (P = 0.96) [Table 2]. Furthermore, the mean level of serum ACE was significantly higher in healthy males compared to male patients (t-test, P = 0.045). Nevertheless, the mean ACE level was not meaningfully different between the females of two groups (t-test, P = 0.90) [Table 2].

Table 2

Mean±Standard deviation of serum angiotensin converting enzyme level in two groups of study

According to the findings presented in Table 2, a significant statistical difference was found between the mean serum ACE levels of various types of pemphigus involvement (P = 0.02). Moreover, pair-wise comparisons with Bonferroni correction showed a significantly higher mean serum ACE levels in patients with cutaneous involvement compared to patients with mucosal involvement (P = 0.02) [Figure 1].

Figure 1

A significant higher mean serum angiotensin-converting enzyme levels in patients with cutaneous involvement compared to patients with mucosal involvement

No significant difference was present in the mean levels of serum ACE of mucocutaneous and cutaneous cases and mucocutaneous and mucosal patients (P = 0.14 and P = 0.51, respectively). This study showed no significant relationship between the age and the serum ACE level of participants (Spearman correlation test, ρ = −0.09 and P = 0.46). In addition, no correlation was found between severity of pemphigus vulgaris (according to PAAS) and serum ACE level of patients (ρ = −0.14 and P = 0.42).

Discussion

Pemphigus vulgaris is an autoimmune blistering skin disease with immunological basis but unknown etiology. Drugs may exacerbate or induce pemphigus. Thiol drugs such as penicillamine and captopril have been studied very well; however, non-thiol drugs, including other ACE inhibitors, e.g., enalapril, ramipril, fosinopril, and the angiotensin II receptor blockers, can be the causative agent of pemphigus.[91011] Because ACE inhibitors can cause pemphigus, we hypothesized that the serum ACE level might be altered in patients with pemphigus vulgaris. Although ACEi may induce pemphigus foliaceous, the scarcity of pemphigus foliaceous cases and the probability that ACE could be an activity marker of the inflammatory disease were the underlying reasons to choose pemphigus vulgaris cases in our study.

According to recent findings, the complete renin angiotensin system (RAS) is present in human skin and plays a role in normal cutaneous homeostasis.[12] One of the key elements of RAS is ACE, which is a zinc metalloendopeptidase. ACE is widely distributed on the surface of endothelial and epithelial cells and removes the carboxy terminal dipeptide from decapeptide angiotensin I to generate angiotensin II, a potent vasoconstrictor, and degrades bradykinin, a vasodilator.[1213] Information about the possible role of ACE in the pathogenesis of skin diseases is little.

Although there are studies evaluating the serum ACE level in dermatoses such as psoriasis and lichen planus, we found no data about ACE level in pemphigus until now.[614]

Huskic et al. showed an increased level of serum ACE in patients with psoriasis and lichen planus, which was compatible with other studies. They did not find any significant difference between the ACE level of different clinical forms of psoriasis.[615] In the current study, the serum ACE level was evaluated in patients with pemphigus vulgaris for the first time. We did not any significant difference between the patients and the control group in our study.

Physiologically, sex and age affect the serum ACE level. The serum ACE level in men is higher than that of women, and the levels decrease with age.[1617] ACE2, which is an ACE homolog, is selectively expressed by adult Leydig cells of the testis[18] and it may be one of the reasons of higher serum ACE level in men. In our study, the mean serum ACE level was higher in male control than in female controls, but we did not find any significant difference in the patient's group. The interesting finding was the significant difference between the mean ACE level of the male patients and controls. It was significantly lower in the male patients. Although it seems that pemphigus should affect males and females equally, there are some studies that suggest pemphigus vulgaris can affect the desmosomes of testis germ cells,[1920] and some other evidence indicate that ACE is positively regulated by androgens.[21] These studies may support our findings of lower ACE level in male pemphigus patients. However, we only suggest that ACE might be lower in male pemphigus patients and we did not make any definite conclusion.

Another interesting finding in our study was the significant increased level of ACE in patients with cutaneous involvement compared with those with mucosal involvement. It may due to this reason that skin is a site of ACE expression.[22] However, further studies with larger samples are required to confirm our result. ACE level also did not show any significant relation with the severity of the pemphigus in our study, whereas in the literatures that worked on psoriasis, the ACE level increased by extent and severity of the skin involvement.[4]

In conclusion, results of the current study showed that in patients with pemphigus vulgaris, the serum ACE level might be altered. Despite the lack of any significant difference in the ACE level of pemphigus and the control group, the mean level was lower in patients and we found a significant difference in the ACE level between our male patients and male control; this indicates ACE might be useful as a disease activity marker in male pemphigus vulgaris patients. This study was the first essay about the relationship of ACE and pemphigus vulgaris with 34 new cases of pemphigus vulgaris. However, our study faced some limitations due to our restricted facilities and PV rarity. The main restriction of our study was the limited number of the new cases of pemphigus and limited statistical power to detect differences based on the small sample size. Another limitation of this study was the lack of evaluation of the level of circulating auto-antibodies in patients. We had only one level of ACE for each participant, which may be another limitation of the current study. Serial measurement of ACE, at least two measurements of ACE on the same patient, may be more valuable. Further studies with larger sample size are required to elucidate any possible alteration of the ACE level in pemphigus patients or any further association of the ACE level in case of mucosal or cutaneous involvement.

What is new?

Angiotensin-converting enzyme (ACE) may play a role in the pathogenesis of pemphigus vulgaris.

Difference in the level of ACE between cutaneous and mucosal pemphigus.