PDGFRß promotes oncogenic progression via STAT3/STAT5 hyperactivation in anaplastic large cell lymphoma.

BACKGROUND: Anaplastic large cell lymphoma (ALCL) is an aggressive non-Hodgkin T cell lymphoma commonly driven by NPM-ALK. AP-1 transcription factors, cJUN and JUNb, act as downstream effectors of NPM-ALK and transcriptionally regulate PDGFRß. Blocking PDGFRß kinase activity with imatinib effectively reduces tumor burden and prolongs survival, although the downstream molecular mechanisms remain elusive. METHODS AND RESULTS: In a transgenic mouse model that mimics PDGFRß-driven human ALCL in vivo, we identify PDGFRß as a driver of aggressive tumor growth. Mechanistically, PDGFRß induces the pro-survival factor Bcl-xL and the growth-enhancing cytokine IL-10 via STAT5 activation. CRISPR/Cas9 deletion of both STAT5 gene products, STAT5A and STAT5B, results in the significant impairment of cell viability compared to deletion of STAT5A, STAT5B or STAT3 alone. Moreover, combined blockade of STAT3/5 activity with a selective SH2 domain inhibitor, AC-4-130, effectively obstructs tumor development in vivo. CONCLUSIONS: We therefore propose PDGFRß as a novel biomarker and introduce PDGFRß-STAT3/5 signaling as an important axis in aggressive ALCL. Furthermore, we suggest that inhibition of PDGFRß or STAT3/5 improve existing therapies for both previously untreated and relapsed/refractory ALK+ ALCL patients.

Immunohistochemical localization of interstitial collagens in bone tissue from patients with various forms of osteogenesis imperfecta.

Immunohistochemical studies of bone from individuals with osteogenesis imperfecta (OI) type II, OI type III, or OI type IV demonstrate a similar pattern, but varying extent, of the abnormal presence of interstitial collagens in bone matrix. OI type II bone had nests of cartilage with type II collagen, and significant type III collagen in the bone matrix. In OI types III and IV, type II collagen was present only in epiphyseal cartilage but bone still contained type III collagen. These findings resembled those in developing fetal bone indicating the "immature" nature of OI bone.

Morphological aspects of basement-membranes and their receptors in benign and malignant neoplasms (review).

We review the current knowledge on alterations of the major basement membrane (BM) components and their cellular integrin receptors in benign and malignant tumors of epithelial and mesenchymal origin. While benign tumors usually exhibit a continous BM, recent analyses provide evidence that invasive growth of carcinomas coincides with (a) a loss in a proper BM, (b) changes in the type of integrin receptor expression and (c) the retained ability of certain tumor cells to synthesize matrix components. This latter aspect has been regarded as a potentially beneficial 'host' mechanism against invasive growth. This assumption is strongly supported by the finding of a positive correlation between the extent of BM loss and both a lesser degree of tumor differentiation and a worse prognosis of tumor growth. The resulting concept indicates that in carcinomas an imbalance in the cell-matrix interaction is the leading element in invasive growth. In mesenchymal tumors a somewhat different role of the BM can be observed. Thus, the qualitative and quantitative expression of major BM components in benign mesenchymal tumors closely relates to the BM pattern of normal tissues providing a histogenetically oriented classification of benign mesenchymal tumors. Most well-differentiated sarcomas retain a BM pattern close to that of the histogenetically related tissue, although in poorly differentiated sarcomas no such attribution to a histogenetic orientation of the tumor cells can be found.

Defective basement membrane in laryngeal carcinomas with heterogeneous loss of distinct components.

In this study, we evaluated immunohistochemically the composition of the tumor-associated epithelial basement membrane (BM) in a series of 66 laryngeal squamous cell carcinomas (SCC) and compared these results with those from 10 cases with laryngeal dysplasia and five cases with normal mucosa (controls). The major BM components collagen IV and VII, laminin-1, perlecan (heparan sulfate proteoglycan), and fibronectin were evaluated. The extent of the retained BM material was quantified by semiautomated morphometry. A subsequent statistical analysis correlated the immunohistochemical findings with the histopathologically evaluated degree of tumor cell differentiation. In our series, we observed a distinct correlation between the degree of tumor cell differentiation and the amount of retained BM material. The loss of BM affected the various components differently, with a more extensive loss of collagen VII even in highly differentiated tumors and a progressive loss of collagen IV immunostaining with decreasing tumor cell differentiation. With respect to the other BM components, a stepwise loss of BM material also was seen with decreasing degree of the tumor cell differentiation. This loss, however was not at a statistically significant level, so these parameters did not show further statistically relevant data. In dysplastic lesions (regardless of the degree of dysplasia), focal BM disruptions were seen that affected the various BM components to a very similar extent. Our observations provide evidence that laryngeal carcinomas show a progressive loss of BM material along with decreasing tumor cell differentiation. This loss of BM, however, affects the various BM components differently. This indicates a dysregulation of the BM, either induced by uncoordinated neosynthesis or selectively enhanced degradation by proteases or both. Finally, the BM analysis may provide information on the biological course of the tumors. The loss of collagen VII may serve as a marker for "early" invasive tumor growth, whereas the amount of collagen IV provides significant information on the loss of tumor cell differentiation.

Parvovirus B19 infection of the fetus. Histology and in situ hybridization.

Fetal tissues from 16 spontaneous abortions, two terminations, and one perinatal death, 18 of which were associated with maternal human parvovirus B19 infection, were examined for B19 infection by histology and in situ hybridization using a digoxigenin-labeled B19-DNA probe. In 15 spontaneous abortions and one termination, erythroblasts with intranuclear inclusions (lantern cells) reacted with B19-DNA by in situ hybridization. No internal or external fetal malformations were observed. Because 13 (86.7%) spontaneous abortions with lantern cells occurred between the 20th and 28th weeks of gestation, it is postulated that B19 infection may be a particular threat to the fetus during this stage of gestation.

Extensive pulmonary haemorrhage in an Egyptian mummy.

We report on the morphological and trace element findings of several internal organs from an Egyptian mummy approximately dating from the year 950 B.C. according to 14C-analysis. By use of a multidisciplinary approach we succeeded in discovering evidence for severe and presumably recurrent pulmonary bleeding during life. This was suggested by the finding of massive haemosiderin deposits in the lung and a selectively and markedly elevated level of iron in trace element analysis of the lung tissue. Furthermore, we observed an enhanced deposition of birefringent particles in the lung tissue, without significant fibrosis. The histological analysis of liver, stomach and intestine confirmed the macroscopic organ diagnoses without evidence of any major pathological processes. In addition, analysis for various drugs revealed a significant deposition of tetrahydrocannabinol (THC), nicotine and cocaine in several organs of the mummy. The concentration profiles additionally provide evidence for a preferential inhalation of THC, while nicotine and cocaine containing drugs seem to have been consumed orally.

Immunolocalization of major interstitial collagen types in human lumbar intervertebral discs of various ages.

We used complete transverse sections through 65 samples of human lumbar intervertebral discs for immunolocalization of the major interstitial collagen types I, II, III, V, VI and IX. The samples were selected from 47 patients ranging in age from 0 (fetuses) to 86 years. The results were compared with the histological findings in disc tissue degeneration and/or reparative alterations as indicated by tear and cleft formation, chondrocyte proliferation, mucous degeneration, granular matrix changes and fibrocartilage fibrillation. We observed a typical pattern for each antibody and each anatomical structure, with, however, remarkable inter- and intraindividual variability, which could be monitored only by use of the complete transverse sections. Accordingly, collagen I was seen in the normal annulus fibrosus and in the degeneratively altered nucleus pulposus, but not within the end-plate, regardless of degenerative changes. Collagens II and IX were found in the normal nucleus pulposus, the inner annulus fibrosus and the end-plate. The collagen II (and IX) staining seemed to be enhanced in areas of minor degenerative lesions, but reduced in advanced lesions and in the degenerated end-plate. Collagens III and VI were significantly increased in areas of minor to advanced degeneration in all anatomical settings, while collagen V showed only minor changes in its staining pattern. In general, histological signs of tissue degeneration coincided with significant quantitative, but also with certain qualitative, changes in the composition of the collagenous disc matrix. These observations indicate the association of degenerative and/or reparative alterations of the intervertebral disc and changes in the collagenous matrix, but document the variability in the extent of the abnormalities observed.

Immunohistochemical analysis of type-X-collagen expression in osteoarthritis of the hip joint.

Conflicting data have been reported on the spatial distribution of type X-collagen expression in osteoarthritis, and no concise data exist on a possible correlation between type X-collagen expression and clinical and radiological alterations. Well defined clinical and radiological data were compared with histopathological and immunohistochemical findings to investigate the expression of type-X collagen in osteoarthritis of the hip joint. Femoral heads were obtained in toto from 11 patients undergoing routine hip arthroplasty for femoral neck fractures (n = 3) or osteoarthritis (n = 8) and from 13 patients (age: 12 days to 69 years) without any evidence of hip-joint pathology. Whole coronal sections from the femoral head were decalcified for routine histology and immunohistochemical analysis with use of type-specific monoclonal antibodies to type-X collagen. Our results demonstrate that type-X collagen is consistently found in osteoarthritic cartilage and is absent from normal adult cartilage (including the region of calcified cartilage). Except for the occurrence of type-X collagen in the middle zone of articular cartilage in advanced stages of osteoarthritis, there is no specific change in the staining pattern or intensity for the collagen during osteoarthritis, particularly when the staining is related to clinical and radiological parameters. Hardly more than 20% of the extracellular matrix stained for type-X collagen; therefore, we suggest that, in most cases, this type of collagen may not play a direct biomechanical role in the weakening of osteoarthritic cartilage but rather may contribute indirectly to a disturbance of the disc biomechanics by altering matrix-molecule interaction. However, expression of type-X collagen may indicate a change in chondrocyte phenotype that consistently coincides with the formation of chondrocyte clusters, one of the first alterations in osteoarthritis visible on histologic examination.

Basement membrane components as differential markers for mesenchymal tumors of various origin.

We immunohistochemically analyzed the presence or absence of a pericellular basement membrane in benign and malignant soft tissue tumors of different origin--of peripheral nerve, smooth and striated muscle, fat tissue, connective tissue, blood and lymph vessels, cartilage and bone--to test the role of the expression of the BM components collagen IV, laminin, heparan sulfate proteoglycan (HSPG) and fibronectin as a differential diagnostic aid. All benign tumors revealed a BM feature corresponding to that of the normal tissue. Well differentiated sarcomas similarly showed a BM pattern close to that of the respective normal mesenchymal cells, so that these sarcomas were attributable to different histogenetic entities. Low differentiated sarcomas preserved in some, but not all, instances a typical BM pattern as well. Since the BM expression in most sarcomas of lesser degree of differentiation shows a distinctive BM pattern, we believe that the BM analysis of soft tissue sarcomas may be useful to establish a proper histogenetic classification of mesenchymal tumors.

Gene expression and protein deposition of major basement membrane components and TGF-beta 1 in human breast cancer.

In the present study we used immunohistochemistry and in-situ hybridization for the localization of major basement membrane (BM) components and their mRNA, respectively, in order to determine the extent of BM production and deposition in normal mammary tissue as well as in invasive mamma carcinomas. While normal mammary tissue showed an intact epithelial BM, as evidenced by a continuous linear staining for collagen i.v., laminin, heparan sulfate proteoglycan (perlecan) and fibronectin, this staining was widely lost in the invasive carcinomas. Non-invasive intraductal areas of the carcinomas (carcinoma-in-situ) revealed focal fragmentation and duplication of the epithelial BM. Using in-situ hybridization, we observed only focally positive mRNA-expression for collagen i.v.-, perlecan- and fibronectin-mRNA in normal glands, while mRNA-signals were significantly enhanced in one case of fibroadenoma and particularly in invasive and non-invasive carcinomas, regardless of the degree of tumor cell differentiation. In these instances both tumor and stroma cells were positively labelled. In addition, we could demonstrate a significant increase in the level of TGF-beta 1-mRNA--as the most active cytokine for the induction of matrix component production--by carcinoma cells and to lesser extent by stroma cells. The discrepancy between significantly enhanced mRNA-synthesis and loss in protein deposition points either to an upregulated activity of matrix degrading proteinases (matrix-metalloproteinases) or a posttranslational block of protein synthesis or both.

Prognostic aspects of the loss of epithelial basement membrane components in preinvasive and invasive laryngeal carcinomas.

The integrity of the epithelial basement membrane (BM) is an essential criterion or the biological behaviour of tumors. Previous studies on various types of carcinomas have demonstrated a good correlation between the amount of retained BM and the course of tumor growth. We therefore evaluated the prognostic significance of the tumor BM in laryngeal carcinomas. In this study, we analyzed 66 cases of laryngeal carcinomas using immunohistochemistry for the visualization of the major BM components collagen IV and VII, laminin-1, heparan sulfate proteoglycan (HSPG, perlecan) and fibronectin. The extent of retained BM-material was quantified morphometrically. A subsequent statistical analysis correlated the immunohistochemical findings with clinical and routine histological parameters, such as the mode of tumor infiltration. All carcinomas showed a defective epithelial BM. In addition, we observed a correlation between the degree of tumor cell-differentiation and the amount of BM material retained. The loss of BM, however, affected the various components differently with an "early" loss of collagen VII. In non-infiltrative dysplastic lesions focal BM disruptions were seen which affected the various BM components very similarly. When we statistically analyzed the correlation between the BM staining pattern and prognostically relevant parameters, collagen VII represented a marker for "early" stroma invasion. It also positively correlated with tumor size/stage, presence of lymph node metastasis and the recurrence of tumor growth. The collagen IV expression was positively correlated with the degree of tumor cell differentiation. The other parameters did not show further prognostically relevant data. Our observations provide significant information on the biological course of the disease. Thus, collagen VII may be a marker for "early" invasive tumor growth, as well as for lymphatic metastasis and local tumor recurrence, while the amount of collagen IV correlates with the tumor cell differentiation.

Determination of fetal age by immunohistochemical estimation of surfactant-producing alveolar type II cells.

We monitored the immunohistochemically determined amount of surfactant-producing alveolar type II cells in human fetal lung using polyclonal antibodies against apoprotein B and C of human pulmonary surfactant. Lungs of 30 dead-born fetuses without lung affection aged between 15 and 38 weeks of gestation were evaluated and the surface density of surfactant-producing alveolar type II cells was determined by morphometry. In lungs of fetuses with a gestational age less than 22 weeks no relevant number of positively reacting cells could be found. Between the 22nd and 29th week a progressive increase with considerable inter-individual variability was observed. From the 30th week on the number of the type II pneumocytes appeared rather constant without further significant increase. We provide evidence that the immunohistochemical detection of surfactant-producing alveolar type II cells is useful for the determination of the age of unknown and especially fragmented fetuses: The lack of surfactant-producing alveolar type II cells in fetal lungs before the 22nd week allows a rather safe distinction between fetal lungs of higher age from those of lesser age. Between the 22nd and 29th week an age-dependent increase in the number of these cells occurs with wide inter-individual variability allowing only an approximate age determination. In particular, this may be an important piece of information in fragmented fetal corpses. Furthermore, the number of surfactant-producing alveolar type II cells provides additional information on pulmonary maturation and may thus be helpful in the estimation of a theoretical survival chance.

Shift of the distribution of age in patients with otosclerosis.

Morphological and biochemical investigations have shown evidence of an association between measles virus and otosclerosis. Epidemiological analysis of age and gender distributions in the 1960s and 1970s revealed a higher incidence of otosclerosis in women, the average age of onset of clinical disturbances and need for surgery being between 15 and 40 years. In the late 1960s and early 1970s a campaign to vaccinate children against measles was started in Germany. The aim of our study was to evaluate whether this campaign has had any influence on the distributions of the age and gender of patients affected by otosclerosis over the past 20 years. The study included patients suffering from clinical otosclerosis who had undergone stapedectomy between 1978 and 1999 and whose clinical data were complete (n = 1351). Statistical analysis during the recruitment period indicated a significant increase in the average age of the otosclerosis patients (p = 0.012). With regard to the gender distribution it was found that the increase of otosclerosis in women compared to men was statistically insignificant (p = 0.418). These data strongly support the hypothesis of a measles virus involvement in otosclerosis and may reflect a decreased incidence of otosclerosis in the generation of patients vaccinated against measles virus.

[Immunohistologic cell characterization of tissue of primary and re-stenoses]. / Immunhistologische Zellcharakterisierung von Gewebe aus Primär- und Restenosen.

Smooth muscle cells and macrophages are essential parts of arteriosclerotic lesions. This study should enable the analysis of different functional and morphological features of cells in primary and restenotic biopsies. Therefore detection of specific cell markers in human arteriosclerotic material derived from directional coronary atherectomy (DCA) of primary and restenotic lesions was used. Cryosections (2-4 microns) were stained immunohistologically (44 samples from 27 patients, 12 restenosis) with monoclonal antibodies. For further analysis antibodies against 5B5 (Prolylhydroxylase), alpha-actin, desmin and collagen I and IV were used. Endothelial structures (CD 31), T-cells and monocyte derived macrophages (CD 68, KP 1) were detected. In a second set-up alpha-actin and CD 68 were double-labelled. Semi-quantitative analysis in relation to total cell count was performed. The tissue removed consisted quantitatively of 78% intima- and 22% media-compartments and thrombus. 40% of the intimal area was comprised of low cellular compartments and in 57% high cellularity and foam-cells were found. In high cellular compartments 81% of the cells were positive for alpha-actin, only 13% of these cells were also positive for desmin. In intimal compartments in 58% of the cells macrophages were detected by CD-68 marker immunohistologically. 87% of these cells showed the expression of the 5B5 antigen (Prolylhydroxylase), in 90% monocytic antigenes were detected. Typical foam cells were not alpha-actin positive, whereas 40% of the CD 68 positive cells were alpha-actin positive. In myofibroblastic cells, positive staining with 5B5, collagen IV and extracellular matrix (collagen I) was present. Staining with antibodies against contractile filaments was diminished compared to the media compartments.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of the tumor markers sialyl Lewis A, sialyl Lewis X, Lewis Y, Thomsen-Friedenreich antigen, galectin-1 and galectin-3 in human osteoblasts in vitro.

AIM: Lewis antigens and the Thomsen-Friedenreich (TF) antigen are complex glycan structures that modulate processes such as cell adhesion and proliferation and tumor metastasis. The aim of our study was to analyze the expression of sialyl Lewis A (sLeA), sialyl Lewis X (sLeX), Lewis Y (LeY), TF, galectin-1 (Gal-1) and galectin-3 (Gal-3) in human osteoblasts in vitro. MATERIALS AND METHODS: The expression of the tumor markers sLeA, sLeX, LeY, TF, Gal-1 and Gal-3 was studied by means of immunohistochemistry on cells grown on chamber slides (2D) and on paraffin sections three-dimensional scaffold-free cultures (3D). The results of the stainings were evaluated semiquantitatively with the immunoreactive scoring system (IRS). RESULTS: Analysis of sLeA expression in both types of culture, 2D and 3D showed no detectable staining. After 5 days, in the 2D culture, expression of sLeX was weak, but the 3D culture (after 56 weeks) displayed a strong expression. LeY was expressed very slightly in the 2D culture, however LeY was not detectable in the 3D culture. The TF epitope was identified in the 2D cell culture model. In the 3D model, however, TF was completely lacking. Gal-1 was expressed very strongly in 2D culture, but in the 3D culture was not detectable. In contrast, Gal-3 was expressed in 3D culture but not in 2D. CONCLUSION: Within this study, we present a systematic analysis of the expression of sLeA, sLeX, LeY, TF, Gal-1 and Gal-3 in human osteoblasts grown in 2D and in 3D scaffold-free cultures. Summarizing the results of our study, we suggest that Lewis antigens and Gal-1 and -3 might play an important role in cell-cell and cell-matrix interactions of osteoblastic cells.

Retinoid X receptor α and retinoids are key regulators in apoptosis of trophoblasts of patients with recurrent miscarriages.

The retinoid X receptor α (RXRα) is a nuclear hormone receptor that is able to bind other nuclear receptors in a heterodimeric complex, thereby activating gene transcription. Recently, we identified enhanced expression of RXRα in extravillous trophoblasts (EVT) and villous trophoblasts (VT) of miscarried placentas. In addition, an increased number of apoptotic EVT was present in miscarried placentas. In this study, on the basis of immunocytochemical analysis, western blots, and quantitative real-time reverse transcription PCR, we could demonstrate a reduced expression of RXRα in choriocarcinoma cell lines and in human VTs after stimulation with the retinoids 9-cis-retinoic acid and all-trans-retinoic acid and the prostaglandin 15-deoxy-Δ(12,14)-prostaglandin J(2). Furthermore, a simultaneous expression of RXRα and the apoptotic marker M30 CytoDEATH in EVT of miscarried placentas from the first trimester was shown. In EVT of control placentas from legal termination of pregnancies, no co-expression of RXRα and M30 could be detected. A likely conclusion is that RXRα plays an important role in the induction of apoptosis. Downregulation of RXRα, as observed in the tested choriocarcinoma cells and trophoblasts, might serve as a protection against apoptosis and miscarriage. In conclusion, RXRα represents a potential target in the treatment of recurrent miscarriages.

Glycodelin A and differentiation of first trimester trophoblast cells in vitro.

AIM: The glycoprotein, glycodelin A (GdA) is a main product of the maternal decidua in the first trimester of pregnancy and is secreted into the amniotic fluid. The purpose of this study was to investigate the effect of GdA on secretion and surface markers of isolated first trimester trophoblasts in vitro. METHODS: Cytotrophoblasts were prepared from human first trimester placentae and incubated with varying concentrations of GdA or transfected separately with the expression plasmid of GdA. Supernatants were assayed for human chorionic gonadotropin (hCG) protein concentrations. Expression of human placental lactogen (hPL), mucin 1 (MUC1) and the Thomsen-Friedenreich (TF) epitope was analysed in stimulated trophoblast cells and in unstimulated controls by immunocytochemistry. RESULTS: Glycodelin A induced a reduced expression of hPL compared with unstimulated controls. Expression of MUC1 was not affected by GdA. Freshly isolated trophoblast cells showed no TF expression but became positive for this antigen after 96 h of cultivation. GdA-stimulated trophoblast cells inhibited TF expression after 96 h of cultivation. GdA plasmids induced a significantly higher hCG production in transfected cells than in cells transfected with the empty plasmid. CONCLUSIONS: The results obtained in this study suggest that GdA is involved in the differentiation of trophoblast cells. The treatment of GdA plasmid transfected trophoblast cells stimulated hCG production in isolated trophoblast cells and inhibited hPL and TF expression, suggesting a functional link between hCG and GdA.

[Immunohistochemical analysis of the basement membrane expression in squamous epithelial carcinoma of the larynx]. / Immunhistochemische Analyse der Basalmembran-Expression beim Plattenepithelkarzinom des Larynx.

Epithelial structures are separated from the stroma by a basement membrane (BM) which serves as a barrier for the epithelial cells. Invasive tumour growth as in laryngeal carcinoma, involves the degradation of this barrier. In our present immunohistochemical analysis, we evaluated both the quantitative and the qualitative changes in the BM composition of 50 laryngeal carcinomas. This analysis comprised the localisation of the BM components collagen IV, laminin, and fibronectin. Furthermore, we applied antibodies against BM components that have not, or only very rarely, been analysed in malignant squamous cell neoplasms--particularly collagen VII and heparan sulfate proteoglycan (HSPG). In this study we provide considerable evidence that varying amounts of preserved BM material can be found in laryngeal carcinoma of different grades of tumour differentiation. Especially by comparison of the different staining patterns for collagen IV and collagen VII, we recognised far more gaps in the staining of the BM by collagen VII than by collagen IV. This fact is underlined by the observation that even in G1 carcinomas collagen VII showed in almost 40% of the cases a complete loss of BM staining. In general, we found a correlation between the amount of preserved BM deposition and the grade of tumour differentiation. This fact may underline the significance of the immunohistochemically detectable amount of BM components as a prognostically relevant parameter.

Localization of extracellular matrix components in congenital nephrotic syndromes.

While renal tissue from one fetus and a newborn with congenital nephrotic syndrome, Finnish type (FCNS), showed a normal basement membrane (BM) localization and composition, in another type of congenital nephrotic syndrome, diffuse mesangial sclerosis (DMS), most glomeruli demonstrated a completely disorganized matrix. In the latter, hyalinized glomerular segments were composed of irregular deposits of interstitial collagens I, III, V, and extensive deposits of heparin sulphate proteoglycan (HSPG), while collagen IV and laminin were completely absent in those areas. Apart from these sclerosed glomerular areas, normal capillarly loops revealed a matrix composition that was comparable to normal glomeruli. The additional immunolocalization of various extracellular matrix components during the development of normal human glomeruli revealed some significant age-dependent changes both in the localization of interstitial collagens and BM components: interstitial collagens I and III disappeared after the first S-shaped indentations appeared, while the interstitial collagen V remained along the glomerular BM and within the mesangium. The BM components showed no significant qualitative changes, but quantitative changes, with a post-natal relative decrease in the collagen IV and laminin content when compared with the level of BM-associated HSPG. Our results provide circumstantial evidence that the composition of the extracellular matrix (and in particular of the BM) shows age-dependent quantitative changes which may be associated with functional adaptation processes of the developing kidney. The observed matrix composition in the two different congenital nephrotic syndromes suggests various pathomechanisms which may be located either in the molecular structure of the negatively charged molecules (e.g. abnormal sulphatation of HSPG in FCNS) or in the dysregulated synthesis of various matrix components (DMS).