생쥐에서 IgA 사구체 신염에 관한 실험적 연구

Abstract

[한글]

IgA신병증(nephropathy)은 면역병리학적으로 신사구체 맥관막 기질내에 주로 IgA의 침착을 특징으로 하는 질병으로, 그 발생빈도가 나라마다 다양하나 우리나라와 지리적 문화적 여건이 유사한 일본에서는 성인에 발생하는 1차적 사구체 신염의 약 40%를 차지하며,

우리나라에서도 비교적 많은 증례가 보고되고 있다. 맥관막 기질내 IgA침착은 타 질병에서도 관찰보고되어 IgA신병증의 본체에 대한 이론이 제기되어 왔으며 그 원인과 기전에 대하여도 이론이 많은 실정이다. 또한 IgA신병증의 유발에 대한 동물실험이 매우 드무나,

최근 경구 면역방법으로 IgA신병증을 유발시켰다는 보고가 있어 많은 관심을 모으고 있다. 그러나 아직 상세한 원인이나 발병기전 뿐 아니라 형태학적 변화에 대한 연구도 미흡한 실정이다.

이에 본 연구자는 20g내외의 자성 ddY마우스에 단백항원인 bovine gamma globulin(BGG), 소아마비 생 및 비활성화 백신을 경구 및 비경구 투여하여 IgA신병증의 유발을 시도하고, 투여방법에 따른 실험적 IgA신병증의 기전을 검토하고저, 단백항원 투여후 실험 제40

, 70, 100일에 실험동물을 도살하여 혈뇨와 단백뇨 및 혈청 IgA양을 측정하였고, 신장, 소장 및 폐장을 광학, 면역형광현미경 및 전자현미경적으로 관찰하여 다음과 같은 결과를 얻었다.

1. 실험군에서는 혈뇨, 단백뇨, 혈청 IgA치의 증가를 볼 수 있었고, 이러한 증가는 BGG투여군보다 소아마비 백신 투여군에서 더 철저하였다.

2. 실험군에서는 신사구체 맥관막 기질에 주로 IgA의 침착과 소량의 IgM및 IgG의 침착이 관찰되었으며, IgA침착은 실험기간이 길수록 증가하는 경향을 보였고, BGG투여군에 비해 소아마비 백신 투여군에서 좀더 뚜렷하였다. 신사구체의 전자현미경적 검사상 각 실험군에서 맥관막 기질의 확장과 맥관막 세포의 증식 및 맥관막내 electron dense deposit이 관찰되었다.

3. 소장 및 폐장의 점막하 IgA함유세포의 수도 정상대조군에 비해 모든 실험군에서 증가되었고, 특히 소아마비 백신 투여군(생 백신 및 비활성화 백신)에서는 경구 및 비경구 투여군 모두에서 실험기간이 길수록 증가되었다.

이상의 소견을 종합하면 BGG, 소아마비 백신(생 백신 및 비활성화 백신)등 이종 단백항원을 마우스에 경구 및 비경구로 투여하여, 면역시키므로서 사람에서와 유사한 IgA신병증이 유발되었으며, 특히 BGG투여보다는 소아마비 백신을 투여하였을 때 더 현저한 IgA신병증을 유발시킬 수 있었다.

[영문]

IgA nephropathy, initially described by Berger and Hinglais is now recognized as a common form of nephritis in many countries. It is characterized by granular mesangial deposits of immunoglobulins, predominantly IgA. Deposits of IgG, IgM, and

C3 are found less often and in smaller quantities than those of IgA. Clinically, most patients have microscopic or macroscopic recurrent hematuria and proteinuria, but as 30% of the patients are asymptomatic, it is usually discovered during a routine physical examination.

Despite a high incidence of IgA nephropathy in certain areas(Japan, France), of the world the pathogenesis of this disease and the contribution of IgA to the renal pathology are net well defined. Recently glomerular deposits of IgA have been shown to be associated with variety of glomerular diseases such as lupus nephritis, Henoch-Schonlein purpura, immune complex type of glomerulonephritis in cirrhosis of liver, and eden in dermatitis herpetiformis, ankylosing spondylitis, mycosis

fungoides, and small cell carcinoma of the lung. However, the mucosal versus systemic origin of the mesangial IgA remains controversial. The existence of sporadic familial cases, together with the presence of immunologic abnormalities in patients' relatives favors immunogenetic aspects of this entity. But due to the complexity of these pathogenetic factors, a rational therapeutic approach is not easy to define.

Experimentally induced IgA nephropathy is rare(Rifai et at, 1979), and furthermore IgA nephropathy nduced by mucosal immunization is extremely rare(Emanicipator et al, 1983).

Therefore the present experiment is undertaken to induce mesangial IgA deposit nephropathy via oral and parentheral immunization, and to investigate the morphological changes of the nephropathy by light, immunofluorescent, and electron microscpic observations.

Material and Methods

Female ddY mice weighing around 20g were used for the experiment, and were divided into four groups as follows:

Group 1 : Normal diet 6 mice

Group 2 : Bovine gamma globulin 15 mice

Group 3 : Poliomyelitis vaccine(live) 15 mice

Group 4 : Poliomyelitis vaccine(inactivated) 15 mice

The Bovine gamma globulin(BGG) was prepared according to Emancipator et al, 1983.

The poliomyelitis vaccine(live) was administered in order to induce mucosal immunization, and the inactivated vaccine for systemic immunization.

Urine protein was measured in fresh urine, using reagent strips. Blood was collected via a cardiac puncture, and the serum was separated and frozen till needed. Serum IgA level were determined by enzyme linked immunosorbent assay.

Fer light microscopical observation, the kidney, small intestine, and lung/bronchus were fixed in 10% neutral formalin. The kidney was examined using H&E, PAS, Trichrome stains, and the ethers by H&E stain.

Fer immunofluorescent microscopic examination, fresh tissues from the kidney, small intestine, and lung/bronchus were processed using routine immunofluorescent antibody technique with Meloy's FITC-conjugated anti-mouse IgG, IgA, ant IgM.

Result and Summary

By oral administration using BGG and poliomyelitis live vaccine, and also by parentheral administration using poliomyelitis inactivated vaccine, the following results were obtained.

1. Hematuria, proteinuria and serum IgA levels were increased in all experimental groups, and were greater in the poliomyelitis vaccine administered groups than in the BGG group.

2. The mesangial deposits were predominantly IgA, but IgM and IgG were also found in minimal degrees. The mesangial IgA deposits increased with time, and were greater in poliomyelitis vaccine administered groups than in the BGG group.

Electron microscopic examination revealed mesangial widening, cellular proliferation, and electron dense deposits in the mesangium.

3. The number of the IgA-containing cells in the small intestine and lung/bronchus increased also with time and were more increased in the poliomyelitis vaccine groups, particularly in the inactivated vaccine group.

In summary, mesangial IgA nephropathy was characteristically induced in mice with inert protein antigens using BGG and poliomyelitis live vaccine, and also by parentheral immunization using poliomyelitis inactivated vaccine. These findings suggest that oral immunization of BGG and poliomyelitis live vaccine, and also parentheral immunization of poliomyelitis inactivated vaccine can induce mesangial IgA nephropathy simulating IgA nephropathy in human.