Antigens comparison FS and El Bagre-EPF

Journal of Dermatological Science (2003) 32 , 33

/

41 www.elsevier.com/locate/jdermsci

Comparative study of autoantigen profile between

Colombian and Brazilian types of endemic pemphigus foliaceus by various biochemical and molecular biological techniques

Yoshiko Hisamatsu

Marilia M. Ogawa

e a,c,1

, Ana Maria Abreu Velez

, Tamotsu Kanzaki

c b,1

, Masayuki Amagai

, Takashi Hashimoto

a,

*

d

,

a

Department of Dermatology, Kurume University School of Medicine, 67 Asahimachi, Kurume, 830-0011

Fukuoka, Japan b

Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA, USA c

Department of Dermatology, Kagoshima University School of Medicine, Kagoshima, Japan d

Department of Dermatology, Keio University School of Medicine, Tokyo, Japan e

Department of Dermatology, Paulista College of Medicine, Sao Paulo, Brazil

Received 30 October 2002; received in revised form 15 January 2003; accepted 16 January 2003

KEYWORDS

Autoimmune bullous disease;

Endemic pemphigus foliaceus;

Enzyme-linked immunosorbent assay;

Immunoblotting;

Desmoglein;

Desmocollin;

Desmosome;

Plakin family protein

Summary Background: Besides Brazilian endemic pemphigus foliaceus (EPF), we have described another focus of EPF in Colombia. Our previous study suggested that

Colombian EPF seemed to react various plakin family proteins, such as envoplakin, periplakin and BP230.

Objective: To further characterize the Colombian EPF and study the difference from Brazilian EPF, we examined the antigen profile of the two types of EPF.

Methods and results: Immunoblotting using normal human epidermal extracts revealed that 38% Colombian EPF sera and 25% Brazilian EPF sera showed IgG antibodies reactive with desmoglein (Dsg) 1, pemphigus foliaceus antigen. The sera of both types of EPF showed protein bands co-migrating with plakin family proteins, particularly periplakin. Immunoblotting analyses using recombinant proteins of various domains of envoplakin, periplakin and BP230 revealed that a considerable number of Colombian EPF sera reacted with recombinant proteins of periplakin, while only few Brazilian sera reacted with some of the recombinant proteins of any plakins.

Enzyme-linked immunosorbent assay (ELISA) for Dsg1 and Dsg3 showed that Dsg1 was reacted by almost all sera of both types of EPF. However, unexpectedly, while none of

Colombian EPF sera reacted with Dsg3, about half of Brazilian EPF sera reacted with

Dsg3.

Conclusion: These results suggested that the Colombian EPF is basically similar to Brazilian EPF in terms that major antigen is Dsg1, but there were some different antigen profiles between the two types of EPF.

– 2003 Japanese Society for Investigative Dermatology. Published by Elsevier Science

Ireland Ltd. All rights reserved.

Abbreviations: ELISA, enzyme-linked immunosorbent assay; EPF, endemic pemphigus foliaceus.

*Corresponding author. Tel.:

/

81-942-31-7571; fax:

/

81-942-34-2620.

E-mail address: hashimot@med.kurume-u.ac.jp

(T. Hashimoto).

1

Joint first authors.

0923-1811/03/$30.00

– 2003 Japanese Society for Investigative Dermatology. Published by Elsevier Science Ireland Ltd. All rights reserved. doi:10.1016/S0923-1811(03)00034-3

34 Y. Hisamatsu et al.

1. Introduction

An endemic pemphigus foliaceus (EPF) was first described in certain regions of Brazil more than a century ago, which is also known as fogo selvagem

[1

/

5] . Another type of EPF has been reported in

Tunisia

[6,7]

. Recently, we have also described additional focus of EPF Colombia

[8

/

10]

(two full papers by Abreu Velez et al., in press). All types of

EPF were characterized histologically by acantholytic intraepidermal blisters and immunologically by circulating IgG autoantibodies that react keratinocyte cell surfaces.

A remarkable feature of EPF is its epidemiological nature. Brazilian EPF is endemic to certain states in Brazil, there are many familial cases including child and young adult cases, most patients are dedicated to farming, and both sexes are equally affected

[2] . On the other hand, the

previous epidemiological studies revealed that

Colombian EPF affects predominantly males at an age of 40

/

60 years, as well as a few postmenopausal females

[8

/

10] . These findings sug-

gest that Colombia EPF differ from Brazilian EPF.

Tunisian EPF also showed different features and affected most frequently females of childbearing age, although its epidemicity has not been well characterized

[6,7] .

In this study, the Colombian EPF is further characterized and the difference between Colombian and Brazilian EPF is studied; we examined autoantigens in both diseases by various biochemical and molecular biological techniques, including immunoblotting and enzyme-linked immunosorbent assay (ELISA) using various antigen sources.

2. Materials and methods

2.1. Patients

In this study, we used sera from 29 Colombian

EPF patients and 20 Brazilian EPF patients, who lived in the endemic areas for both diseases and showed typical clinical and histological features each of Colombia EPF and Brazil EPF. We also used two sera each from typical cases of pemphigus vulgaris, pemphigus foliaceus, paraneoplastic pemphigus and bullous pemphigoid as positive controls, as well as 10 normal control sera.

2.2. Immunofluorescence studies

Indirect immunofluorescence using sections of normal human skin for both IgG and IgA antibodies was performed as described previously

[1,3] .

2.3. Immunoblotting studies

We performed various immunoblotting procedures using different antigen sources to identify possible autoantigens reacted by EPF sera. Immunoblotting of normal human epidermal extracts was performed as described previously

[4,11

/

15] .

Recently, we have successfully produced recombinant fusion proteins of envoplakin (EPL), periplakin

(PPL) and BP230, which are members of plakin family protein

[16,17] . All the plakin family pro-

teins show similar molecular structures, consisting of N-terminal globular domain (N), middle rod domain (M) and C-terminal globular domain (C)

[18

/

21]

. It is now confirmed that these plakin family proteins are autoantigens targeted by paraneoplastic pemphigus sera

[22

/

27] . We generated

domain-specific recombinant fusion proteins, named EPL-N, M, C, PPL-N, M, C and BP230-N, M,

C

[16,17] . Immunoblotting using these recombinant

proteins was performed as described previously

[16,17]

. Because the fusion proteins of ENV-N, ENV-

M, PPK-N, PPK-M, BP230-N, BP230-M and BP230-C could not be purified by glutathione

/ sepharose column, the patients sera were pre-absorbed with bacterial lysate to reduce background reactivity due to non-specific antibodies to bacterial proteins

[16,17]

.

2.4. ELISA of desmoglein (Dsg) 1 and Dsg3

ELISA of Dsg1 and Dsg3 for IgG antibodies was performed as described previously

[28

/

30] . In this

ELISA for IgG antibodies, the index value above 20 was considered positive and the value between 10 and 20 was in the gray zone. We also performed

ELISA of Dsg1 and Dsg3 for IgA antibodies, which has recently been developed

[31] .

2.5. ELISA of desmocollin (Dsc) 1, 2 and 3

We have recently produced recombinant proteins of extracellular domains of human Dsc1

/

3 using baculovirus expression system (Hisamatsu et al., submitted for publication). Using the recombinant proteins, we have developed a novel ELISA for detecting antibodies of both IgG and IgA classes against Dsc1

/

3 (Hisamatsu et al., submitted for publication). The details for the ELISA of Dsc1

/

3 are described in a separate manuscript (Hisamatsu et al., submitted for publication). Procedures are almost the same as that for ELISA of Dsg1 and Dsg3

[28

/

30]

, with some modifications. All the normal control sera showed the value of OD

490 less than

0.03. Therefore, we arbitrarily set the cut-off value as 0.1 for both IgG and IgA antibodies. In

Comparison of antigen between two types of endemic pemphigus foliaceus 35 general, none of the 45 sera of classic types of pemphigus; i.e. pemphigus vulgaris and sporadic pemphigus foliaceus, showed positive reactivity.

2.6. COS-7 cell transfection study using human Dsc1

/

3 cDNA

cDNA transfection study to detect IgA antibodies to Dsc1, 2, or 3 cDNAs was performed, as described previously

[32] .

3. Results

The results of all experiments are summarized in

Table 1 .

3.1. Immunofluorescence studies

By indirect immunofluorescence using sections of normal human skin, the sera of all the 29

Colombia EPF and 20 Brazil EPF patients showed

IgG anti-cell surface antibodies (data not shown).

In addition, two Colombian EPF sera showed IgA anti-cell surface antibodies reactivity with upper epidermis, while none of Brazilian EPF showed IgA antibodies.

3.2. Immunoblotting studies

By immunoblotting using normal human epidermal extracts, 11 (38%) of 29 Colombian EPF sera and 5 (25%) of 20 Brazilian EPF sera showed a 160 kDa protein band, which co-migrated with Dsg1 detected by control non-endemic pemphigus folia-

ceus sera ( Fig. 1 a,b). However, numerous addi-

tional protein bands were seen in blots reacted by both EPF sera (

Fig. 1 a,b). Particularly, 14 (48%) of

Colombian EPF sera reacted clearly with a 190 kDa protein band, which co-migrated with periplakin detected by control sera of paraneoplastic pemphigus (

Fig. 1 a). In addition, some patients weakly

reacted with 230 and 210 kDa protein bands, which co-migrated with BP230 and envoplakin detected by control sera of bullous pemphigoid and para-

neoplastic pemphigus, respectively ( Fig. 1 a). These

protein bands co-migrating with various plakin family proteins were also frequently detected by

Brazilian EPF sera ( Fig. 1 b).

In immunoblot analyses using recombinant proteins of EPL-N,M,C, PPL-N,M,C and BP230-N,M,C, the most interesting result was that 13

/

31% of

Colombian EPF sera reacted with various domains of periplakin, particularly frequently with N- and Cterminal domains of the protein, whereas only few

Table 1 Summary of the results of all experiments

Colombian EPF Brazilian EPF

Immunoblotting of epidermal extracts

230 kDa BP230 2/29 (7%)

210 kDa envoplakin 2/29 (7%)

190 kDa periplakin 14/29 (48%)

160 kDa Dsg1 11/29 (38%)

130 kDa Dsg3 0/29 (0%)

1/20 (5%)

5/20 (25%)

10/20 (50%)

5/20 (25%)

1/20 (5%)

Immunoblotting of recombinant proteins

EPL-N 2/29 (7%)

EPL-M

EPL-C

4/29 (13%)

0/29 (0%)

0/20 (0%)

3/20 (15%)

0/20 (0%)

PPL-N

PPL-M

PPL-C

9/29 (31%)

4/29 (13%)

8/29 (27%)

1/20 (5%)

1/20 (5%)

3/20 (15%)

0/20 (0%)

1/20 (5%)

1/20 (5%)

BP230-N

BP230-M

BP230-C

ELISA

Dsg1 (IgG)

Dsg3 (IgG)

Dsg1 (IgA)

Dsg3 (IgA)

Dsc1 (IgG)

Dsc2 (IgG)

Dsc3 (IgG)

1/29 (3%)

0/29 (0%)

0/29 (0%)

27/29 (93%)

0/29 (0%)

0/2 (0%)*

0/2 (0%)*

0/29 (0%)

0/29 (0%)

0/29 (0%) cDNA transfection to COS-7 cells

Dsc1 (IgA) 0/2 (0%)*

Dsc2 (IgA)

Dsc3 (IgA)

0/2 (0%)*

0/2 (0%)*

20/20 (100%)

12/20 (60%)

3/20 (15%)

1/20 (5%)

3/20 (15%)

3/20 (15%)

3/20 (15%)

Not done

Not done

Not done

* Two cases with IgA anti-cell surface antibodies.

Brazilian EPF sera reacted with some of the periplakin recombinant proteins (

Fig. 2

). In contrast with the results of periplakin recombinant proteins, only a few (less than 15%) of sera of both types EPF reacted with some of envoplakin recombinant proteins (

Fig. 3 ). Furthermore, concerning

the recombinant proteins of BP230, any recombinant proteins were rarely detected by the sera of

both types of EPF ( Fig. 4 ).

3.3. Results of ELISA of Dsg1 and Dsg3

Twenty-seven (93%) of 29 Colombia EPF sera and all 20 Brazil EPF sera showed IgG antibodies to Dsg1 by ELISA. Interestingly, whereas none of Colombia

EPF sera reacted with Dsg3, seven Brazil EPF sera reacted with Dsg3 and five Brazil EPF sera weakly reacted with Dsg3 (in the gray zone) (

Fig. 5

).

In addition, we examined all 20 Brazilian EPF sera by ELISA of Dsg1 and Dsg3 for IgA antibodies.

Three and one sera showed positive reactivity with

36 Y. Hisamatsu et al.

Fig. 1 The results of immunoblotting using normal human epidermal extracts. Two separate experiments were performed for Colombian EPF (a) and for Brazilian EPF (b). In each panel, the lanes showed reactivity of EPF patients

(Pt), control PV serum (PV), control paraneoplastic pemphigus serum (PNP), control bullous pemphigoid serum (BP), and monoclonal antibodies to Dsc (Dsc-mAb) and to desmoplakin (DPL-mAb). The positions of protein bands are shown in the left of each panel.

Dsg1 and Dsg3, respectively. Because two Colombian EPF sera showed IgA anti-cell surface antibodies by indirect immunofluorescence, we also examined the two sera by ELISA of Dsg1 and Dsg3 for IgA antibodies. However, neither serum reacted with any Dscs.

3.4. Results of ELISA of Dsc1

/

3

As we mention in detail in a separate study

(Hisamatsu et al., submitted for publication), by the ELISA of Dsc1

/

3, 3 of the 20 Brazilian EPF sera reacted with all Dsc1

/

3 (

Fig. 6 ). In contrast, no

Colombian EPF sera showed positive reactivity, although a few sera showed a weak reactivity

within the gray zone ( Fig. 6 ).

3.5. Results of cDNA transfection method

To study the antigens for IgA antibodies in the two Colombian sera which showed IgA anti-cell surface antibodies, we performed the cDNA transfection method. However, IgA antibodies in the two sera did not show any positive reactivity with all

Dscs (data not shown).

4. Discussion

In our previous study, we showed that 12 of 27

Brazilian EPF sera reacted with Dsg1 by immunoblotting of epidermal extracts, which is consistent with the results that about one-third of sporadic pemphigus foliaceus sera react with Dsg1, suggesting the similarity between the two diseases

[4] . In

the present study, we further confirmed that all the Brazilian EPF sera reacted with Dsg1 by ELISA, which has been shown to be a highly sensitive and specific method

[28

/

30] . The reason why only one-

third of the sera of EPF and sporadic pemphigus foliaceus reacted with Dsg1 by immunoblotting was considered that the epitopes detected by the sera are destroyed during the procedure of immunoblotting, while such epitopes are retained in the

ELISA.

In addition, 38% Colombian EPF sera reacted with

Dsg1 by immunoblotting, and almost all Colombian

EPF sera showed anti-Dsg1 antibodies by ELISA, which was very similar to the results of Brazilian

EPF, suggesting that the Colombian and Brazilian

EPF have common nature as a subtype of pemphigus foliaceus.

However, a striking finding was that more than half of Brazilian EPF showed antibodies to Dsg3, pemphigus vulgaris antigen, by the ELISA. This result is in contrast to the result of sporadic pemphigus foliaceus, which showed no positive reactivity with Dsg3 by this ELISA

[28,30]

. We could not detect the reactivity with Dsg3 in any Brazilian

EPF by immunoblotting, which may be due to the relatively low titer of anti-Dsg3 antibodies in the sera.

Interestingly, none of Colombia EPF sera reacted with Dsg3 by ELISA. This specific reactivity of

Brazilian EPF with Dsg3 is also in clear contrast to the result that none of sporadic pemphigus foliaceus sera showed antibodies to Dsg3 by the same

ELISA

[28

/

30] .

Comparison of antigen between two types of endemic pemphigus foliaceus 37

Fig. 2 The results of immunoblotting of recombinant proteins of various domains of envoplakin. Left panel shows the results of representative Colombian EPF sera with recombinant proteins of EPL-N, EPL-M and EPL-C, and right panel shows the results of representative

Brazilian EPF sera. The right lane in each panel showed the reactivity of a control paraneoplastic pemphigus serum (PNP). An arrow in the left in each panel indicates the position of intact recombinant protein.

The significance of the results that a few

Brazilian EPF sera showed IgA anti-Dsg antibodies is at the present unknown.

In our previous study, we found that, in addition to Dsg1, Colombian EPF sera reacted with many other protein bands by various immunoblotting and immunoprecipitation analyses, particularly, 230,

210 and 190 kDa proteins, which were considered to be BP230, envoplakin an periplakin, respectively

(Abreu Velez et al., in press). In the present study, we further found the reactivity of many Colombian

EPF sera with multiple proteins by immunoblotting of human epidermal extracts, which was not used in the previous study (Abreu Velez et al., in press).

To confirm the reactivity of Colombian EPF sera with these plakin family proteins (also know as paraneoplastic pemphigus antigens), we examined

Fig. 3 The results of immunoblotting of recombinant proteins of various domains of periplakin. Left panel shows the results of representative Colombian EPF sera with recombinant proteins of PPL-N, PPL-M and PPL-C, and right panel shows the results of representative

Brazilian EPF sera. The right lane in each panel showed the reactivity of a control paraneoplastic pemphigus serum (PNP). An arrow in the left in each panel indicates the position of intact recombinant protein.

sera of both Colombian and Brazilian EPF by immunoblotting using various domain-specific recombinant proteins of these proteins. These studies further indicated that considerable number of

Colombian EPF sera reacted with various domains of periplakin, while only few of Brazilian EPF sera reacted with some of them. Recombinant proteins of envoplakin were recognized by less number of sera of both types of EPF. These results are similar to those in our previous study

[16] , which indicated

that a few sera of non-paraneoplastic pemphigus patients react with either envoplakin or periplakin.

However, the number of the Colombian EPF sera reactive with envoplakin recombinant proteins are significantly higher, indicating that the preferential reactivity with periplakin may be characteristic of

Colombian EPF.

38 Y. Hisamatsu et al.

Fig. 5 The results of ELISA of Dsg1 and Dsg3 for IgG antibodies. Upper and lower panels showed the results of

ELISA for Dsg1 and Dsg3, respectively. In each panel, the results of Colombian EPF sera were shown in the left and the results of Brazilian EPF sera in the right. The dashed horizontal lines indicate the cut-off levels (index value

20).

Fig. 4 The results of immunoblotting of recombinant proteins of various domains of BP230. Left panel shows the results of representative Colombian EPF sera with recombinant proteins of BP230-N, BP230-M and BP230-C, and right panel shows the results of representative

Brazilian EPF sera. The right lane in each panel showed the reactivity of a control bullous pemphigoid serum

(BP). An arrow in the left in each panel indicates the position of intact recombinant protein.

In clear contrast, the sera of both types of EPF rarely reacted with any BP230 recombinant proteins, which is consistent with the results of our previous study

[17] , that any BP230 recombinant

proteins were detected by non-bullous pemphigoid sera. Therefore, it seems likely that, although the

230 kDa protein band detected by some Colombian

EPF sera in our previous study (Abreu Velez et al., in press), the 230 kDa protein was other protein with molecular weight of 230 kDa, but not BP230.

In our previous studies, we have found that some

Brazilian EPF sera showed IgG antibodies reactive with bovine Dsc

[33] . However, the significance of

these findings was not clear because none of these sera reacted with human Dsc. In this study, a few

Brazilian EPF sera, but no Colombian EPF sera, showed a positive IgG reactivity with Dsc1

/

3 by

ELISA of Dsc1

/

3. Although the specificity of this reactivity could not be confirmed, the results with this novel ELISA may further suggest that Brazilian

EPF sera, but not Colombian EPF sera, contain anti-

Dsc antibodies.

Finally, we found that two Colombian EPF sera showed IgA antibodies, which reacted with cell surfaces in the upper epidermis. Because this distribution is that of Dsc1, we considered that these sera may contain IgA antibodies to Dsc1.

However, IgA antibodies in the sera did not react with any Dsc by either ELISA of Dsc1

/

3 or cDNA transfection method for Dsc1

/

3.

The results of the present study first indicate that, although the both Colombian and Brazilian

EPF showed similar reactivity in terms of Dsg1, there were several clear differences in immunoreactivity between the two EPF.

One finding was that, while more than half of

Brazilian EPF reacted with Dsg3 by ELISA, none of

Colombian EPF reacted with Dsg3. The next finding was that, while Colombian EPF preferentially reacted with the recombinant proteins of various domains of periplakin, only few Brazilian EPF sera reacted with them. Furthermore, some Brazilian

Comparison of antigen between two types of endemic pemphigus foliaceus 39

Fig. 6 The results of ELISA of Dsc1-Dsc3 for IgG antibodies. Upper, middle and lower panels showed the results of ELISA for Dsc1, Dsc2 and Dsc3, respectively. In each panel, the results of Colombian EPF sera were shown in the left and the results of Brazilian EPF sera in the right. The dashed horizontal lines indicate the cutoff levels (OD 0.1).

EPF sera showed positive reactivity in ELISA of

Dsc1

/

3 for IgG antibodies.

These results indicated that, although both

Colombian and Brazilian types of EPF seemed to be subtypes of pemphigus foliaceus, there is a considerable difference in their immunopathological features between the two EPF. These differences may be consistent with the different findings in both clinical and epidemiological characteristics between the two EPF, which were indicated by the previous study (Abreu Velez et al., in press).

However, in contrast that sera of classic types of pemphigus rarely react with antigens other than

Dsgs, both Colombian and Brazilian EPF sera reacted with a variety of desmosomal proteins by various techniques.

The reason why both types of EPF show such a highly immunogenic condition in the patients is not known. However, the previous study showed that even the relatives both in Brazilian EPF and in

Colombian EPF (Abreu Velez et al., submitted for publication). These results lead us to speculate that, in conjunction with genetic predisposition, some triggers, such as exposure to micro-organisms, may induce a highly immunogenic state in the patients, resulting in production of antibodies to many self antigens. Epitope spreading mechanism may be involved in the production of multiple autoantibodies

[34] .

In addition, because Colombian EPF sera preferentially reacted with paraneoplastic pemphigus antigens, there may be a similar pathomechanism in autoantigen production in Colombian EPF and paraneoplastic pemphigus, although the two diseases are quite different clinically and epidemiologically.

The endemic autoimmune diseases are very rare, and EPF is a typical example for this condition, which should give us many clues to unravel the pathomechanisms in development of autoimmunity. In this respect, the various interesting and complex autoantigen profiles found in both Colombian and Brazilian EPF in this study should be important to understanding the pathogenesis of these diseases, although the significance of the results is not clear at present.

In conclusion, the results of the present study indicated that, although both Colombian and Brazilian EPF are similar diseases in terms of the reactivity with Dsg1, there is considerable variability with reactivity with other desmosomal proteins, indicating some difference between the two diseases. The significance of the complex autoantigen profile in these diseases should be clarified in future studies.

Acknowledgements

We gratefully thank Dr. Marilia M. Ogawa for generously providing us with the sera of Brazilian

EPF. We thank Miss Michiyo Noge, Miss Yuko

Kawano, and Miss Ayumi Suzuki for their technical assistance, and Miss Akiko Tanaka for secretarial assistance. This work was supported by Grant-in-

Aid for Scientific Research from the Ministry of

Education, Science and Culture of Japan, and a grant from the Ministry of Health and Welfare of

Japan. Dr. Hisamatsu was an awardee of the

Professor Klingman Award for travel expense for the Annual Meeting for the Society of Investigative

Dermatology in 2001 (Washington, DC).

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