[Nephropathy in pregnancy--an endothelial lesion?].

Morphological examination of renal biopsies from 90 women with preeclampsia (PE), assessment of the clinical data and clinicomorphological correlations produced the following results: 1. By light-microscopy the renal lesions in PE imitate a picture of glomerulonephritis of mesangial type with different degrees of severity. 2. Morphometric investigations confirmed the impression gained by light-microscopy of swelling of endothelial cells and podocytes as well as endocapillary cell proliferation and enlargement of the glomeruli. 3. The immunohistological findings are non-specific and argue against immune complex deposition, but are suggestive of insudative processes. In addition immunohistological investigations of fibronectin and factor VIII-associated antigen reveal a pathogenetic relevant alteration of endothelial cell. 4. Electronmicroscopy is the most valid diagnostic method allowing subdivision of the quantitative different lesions in various degrees of severity. Furthermore the use of this method allows elucidation of the dynamics of the underlying disease process, which progresses through successive stages i.e. early, fully developed and late stage, supporting the reversibility of these glomerular lesions. 5. Close correlations are found between the clinical parameters and morphological findings in nephropathy in pregnancy-induced hypertension. The hypertension, proteinuria and nephrotic syndrome, which characterize the clinical picture, correlate with the severity of the glomerular lesions and the further course of the disease. Moreover, hypertension also correlates with mesangial and subendothelial deposits and with focal segmental hyalinosis and sclerosis, occurring in some cases. The focal segmental hyalinosis and sclerosis should be regarded as hyperperfusion-lesions indicating benign nephrosclerosis and developing only facultatively in PE. 6. The first morphological substrate of nephropathy in pregnancy-induced hypertension with the key to pathogenesis present itself as endothelial lesion, possibly caused by oxygen free radicals, lipid-peroxides or hyperfusion. In result of the endothelial lesion an imbalance of the different mediator systems i.e. thromboxane-prostacyclin, endothelin-EDRF with dominance of vasoconstrictive reactions would be effective. Thus the following induction of coagulative, vasoconstrictive and proliferative processes results in the characteristic glomerular lesions in PE.