Expression of type III collagen mRNA in renal biopsy specimens of patients with idiopathic membranous glomerulonephritis

Aim-To investigate the distribution of type III collagen in membranous glomerulonephritis (MGN); to identify the cells responsible for the synthesis of alpha1 (III) mRNA.method-The distribution of type III collagen was studied by immunohistochemistry in 10 renal biopsy specimens, histologically diagnosed as MGN, and five control renal tissue samples obtained at surgery. Synthesis of alpha1 (III) mRNA was detected by non-radioactive in situ hybridisation.Results-On immunohistochemistry, type III collagen was not observed in the control glomeruli, but was present focally in the glomeruli in samples from patients with MGN. No specific hybridisation signal for alpha1 (III) mRNA was found in the control glomeruli on non-radioactive in situ hybridisation. By contrast, positive signals for alpha1 (III) chain mRNA were detected in glomerular epithelial cells and mesangial cells in MGN tissue samples.Conclusion-These data suggest that additional synthesis of type III collagen by intraglomerular cells contributes to the changes in the glomerular basement membrane characteristic of MGN.

Amelioration of the premature ageing-like features of Fgf-23 knockout mice by genetically restoring the systemic actions of FGF-23

Genetic ablation of fibroblast growth factor 23 from mice (Fgf-23(-/-)) results in a short lifespan with numerous abnormal biochemical and morphological features. Such features include kyphosis, hypogonadism and associated infertility, osteopenia, pulmonary emphysema, severe vascular and soft tissue calcifications, and generalized atrophy of various tissues. To determine whether these widespread anomalies in Fgf-23(-/-) mice can be ameliorated by genetically restoring the systemic actions of FGF-23, we generated Fgf-23(-/-) mice expressing the human FGF-23 transgene in osteoblasts under the control of the 2.3 kb alpha1(I) collagen promoter (Fgf-23(-/-) /hFGF-23-Tg double mutants). This novel mouse model is completely void of all endogenous Fgf-23 activity, but produces human FGF-23 in bone cells that is subsequently released into the circulation. Our results suggest that lack of Fgf-23 activities results in extensive premature ageing-like features and early mortality of Fgf-23(-/-) mice, while restoring the systemic effects of FGF-23 significantly ameliorates these phenotypes, with the resultant effect being improved growth, restored fertility, and significantly prolonged survival of double mutants. With regard to their serum biochemistry, double mutants reversed the severe hyperphosphataemia, hypercalcaemia, and hypervitaminosis D found in Fgf-23(-/-) littermates; rather, double mutants show hypophosphataemia and normal serum 1,25-dihydroxyvitamin D(3) levels similar to pure FGF-23 Tg mice. These changes were associated with reduced renal expression of NaPi2a and 1 alpha-hydroxylase, compared to Fgf-23(-/-) mice. FGF-23 acts to prevent widespread abnormal features by acting systemically to regulate phosphate homeostasis and vitamin D metabolism. This novel mouse model provides us with an in vivo tool to study the systemic effects of FGF-23 in regulating mineral ion metabolism and preventing multiple abnormal phenotypes without the interference of native Fgf-23.

Clinicopathological study of vesicoureteral reflux (VUR)-associated pyelonephritis in renal transplantation

We retrospectively studied the occurrence of vesicoureteral reflux (VUR)-associated pyelonephritis using renal biopsies obtained from the transplanted kidneys, and correlated the histological changes with clinical parameters. Out of a total of 131 renal biopsies performed between 1990 and 2001 on renal transplant patients at the department of Urology of Nagasaki University Graduate School of Biomedical Sciences, 12 patients showed pyuria more than twice in a single year. Seven of these 12 patients were available for determining VUR by voiding cystourethrography (VCUG). Cystoureterography demonstrated VUR in three of seven studied patients with pyuria. A histopathological examination revealed dilatation of both proximal and distal tubules in renal biopsies of transplant patients with VUR, compared to renal biopsies of transplant patients without VUR, or non-transplanted patients with thin membrane disease. One of the patients with VUR showed advanced features of chronic pyelonephritis in four consecutive biopsies at different time points, suggesting a late stage of reflux nephropathy in the transplanted kidney. We conclude from our study that the occurrence of VUR-related pyelonephritis may be one of the important long-term complications in the survival of renal allografts.

Collagens, collagen-binding heat shock protein 47 and transforming growth factor-beta 1 are induced in cicatricial pemphigoid: possible role(s) in dermal fibrosis

Cicatricial pemphigoid (CP) is an autoimmune mucocutaneous blistering disease associated with scarring. Heat shock protein 47 (HSP47) is thought to play an important role in fibrogenesis, but its role in skin lesions of cicatricial pemphigoid is not yet known. In the present study, we examined the role of HSP47 in dermal fibrosis in cutaneous lesions of a CP patient. Skin biopsies from a patient with CP, and from normal subjects were studied for the expression of HSP47, and interstitial collagens (type I and type III collagens) by immunohistochemistry. Dermal fibroblasts isolated from skin of normal individuals and from fibrotic skin of a CP patient were used to study the expression of HSP47, transforming growth factor beta 1 (TGF-beta 1), type I and type III collagens. Compared to the control skin sections, an increased expression of HSP47 was associated with an increased deposition of interstitial collagens in the fibrotic skin section of the CP patient. Similarly, in contrast to control dermal fibroblasts, the fibroblasts isolated and cultured from fibrotic skin of the CP patient, and grown in vitro, exhibited increased expression of HSP47, type I and type III collagens. Furthermore, compared to the normal control fibroblasts, an increased expression of TGF-beta 1 was detected in the dermal fibroblasts isolated from fibrotic skin of the CP patient. When dermal fibroblasts were treated with various concentrations of TGF-beta 1 (6.25, 12.5, 25, 50 and 100 ng/ml for 24 h), it induced the expression of both type I collagen and HSP47, as determined by quantitative real-time PCR. In conclusion, the expression of TGF-beta 1, HSP47, type I collagen and type III collagen was up-regulated in the fibrotic skin of CP patient, and a complex interaction of these molecules may initiate and propagate the fibrotic cascade in the skin of CP patients.

Lipid formulations of polyene antifungal drugs and attenuation of associated nephrotoxicity

Amphotericin B is an effective broad-spectrum antifungal agent, but various side effects, especially nephrotoxicity, have restricted its use. Recently, lipid formulations of amphotericin B have been developed in order to reduce its toxic side effects. Clinical trials, although in the early stages, suggest promising results, and that some of these lipid formulations are potent and less toxic, even at higher doses. We summarize herein the existing information about newer lipid formulations of polyene antifungal drugs, which could attenuate associated nephrotoxicity.

The renal expression of heat shock protein 47 and collagens in acute and chronic experimental diabetes in rats

Glomerulosclerosis and tubulointerstitial fibrosis are the main structural changes found in the later stages of diabetic nephropathy, which is clinically characterized by proteinuria, and progressive renal insufficiency. Heat shock protein (HSP) 47, a collagen-binding stress protein, has a specific role in the intracellular processing of procollagen molecules during collagen synthesis. It is implicated in the pathogenesis of various fibrotic diseases. However, the expression and significance of HSP47 in acute and chronic phases of diabetic nephropathy is not yet known. In this study, we studied the expression of HSP47 in the kidneys obtained from streptozotocin-induced diabetic rats, in both short- and long-term diabetes. To determine the renal expression of HSP47, and collagens (type III and IV) in acute (days 1, 3 and 14) and chronic (weeks 4, 12 and 24) diabetes, we have performed a time-course study using streptozotocin-induced diabetic rats. The expression pattern of alpha-smooth muscle actin (to identify mesangial cell damage), vimentin (to identify tubular epithelial cell damage), and desmin (to identify glomerular epithelial cell damage) was also determined in kidneys of these diabetic rats. Antibodies specific for HSP47, type III and type IV collagens, alpha-smooth muscle actin, vimentin, and desmin were used to assess the relative expression of their proteins in paraffin-embedded kidney sections by immunohistochemistry. Compared to control rat kidneys, no significant changes in the expression of HSP47 was found in the kidneys of acute diabetic rats. However a significant increase in the expression of HSP47 was noted in the kidneys of chronic diabetic rats; increased expression of HSP47 correlated with an increased renal deposition of types III and IV collagens. Similarly, compared to kidneys of control and acute diabetic rats, an increased expression of alpha-smooth muscle actin (in mesangial cells), vimentin (in tubular epithelial cells), and desmin (in glomerular epithelial cells) was detected in the kidneys of chronic diabetic rats; by dual immunostaining, these phenotypically-altered renal cells in kidneys of chronic diabetic rats were found to be HSP47-producing cells. Importantly, HSP47 up-regulation coincided with the initiation and progression of renal fibrosis, as determined by the expression and deposition of collagens. Our results strongly support a pathological role for HSP47 in the later stages (sclerotic phase) of streptozotocin-induced diabetic nephropathy, which is associated with glomerulosclerosis and tubulointerstitial fibrosis.

Tissue and molecular events in human conjunctival scarring in ocular cicatricial pemphigoid

Detailed histomorphometric analysis of human conjunctival biopsy specimens has convincingly demonstrated that tissue remodeling of the extracellular matrix (ECM) is an essential and dynamic process associated with conjunctival scarring in ocular cicatricial pemphigoid (OCP). The conjunctival scarring often eventually results in impaired vision and/or blindness. The molecular mechanisms of conjunctival scarring are not completely understood. Accumulating evidence indicates that the early phase of conjunctival fibrosis is linked with an immuno-inflammatory process mediated by cytokines released by activated conjunctival cells and/or by infiltrating cells. Fibrogenic cytokines secreted by inflammatory cells and fibroblasts might actively be involved in remodeling of the matrix within the conjunctival stroma, possibly by regulating the altered metabolism of matrix proteins.

In vitro organ culture model for mucous membrane pemphigoid

Mucous membrane pemphigoid (MMP), also known as cicatricial pemphigoid, is a rare vesiculobullous disease of mucosal tissues, which involves the oral, ocular, and other mucous membranes. We have studied a group of patients with histologically and immunopathologically proven pemphigoid disease involving predominantly the conjunctiva and oral mucosa in addition to other mucosae. The purpose of our study was to (i) demonstrate the specific binding of autoantibodies present in the sera of patients with MMP to normal human oral mucosa by indirect immunofluorescence (IIF) and (ii) to study the role of these autoantibodies in the pathogenesis of subepithelial blister formation using normal human buccal mucosa in organ culture. Serum and IgG fractions from MMP patients showed homogeneous smooth linear binding along the basement membrane zone (BMZ) of the normal buccal mucosa on IIF. Serum from pemphigus vulgaris patients showed intercellular or keratinocyte cell surface staining. BMZ separation developed at 48 h after incubation of normal human buccal mucosa in organ culture, with serum or IgG from patients with MMP but not after addition of normal human serum. Addition of pemphigus vulgaris serum to the in vitro culture of normal human buccal mucosa showed acantholysis. This preliminary report suggests that circulating autoantibodies may have an important role in the pathogenesis of MMP. This in vitro organ culture model will facilitate enhancing our understanding of various molecular events during the process of blister formation in MMP and in the study of other mucosal diseases.

Identification of ocular cicatricial pemphigoid antibody binding site(s) in human beta4 integrin

PURPOSE

To identify specific site(s) on human ss4 molecule to which sera from ocular cicatricial pemphigoid (OCP) patients bind and to determine its role in the process of blister formation.

METHODS

Clone the fragments representing the extracellular and intracellular domain of ss4 molecule from normal human conjunctival mRNA into an expression vector; map the region to which sera from OCP patients bind by Western blot analysis. Determine the role of the immunodominant region in pathogenesis by demonstrating the ability of the rabbit antibody to the immunodominant region to produce separation of basement membrane zone (BMZ) from the basal epithelial layer when incubated with normal human conjunctiva in an in vitro organ culture model.

RESULTS

Majority of the OCP sera tested bound to the C-terminal end of the intracellular domain (IC3.0) of the human ss4 integrin. Further subcloning of IC3.0 demonstrated that a smaller fragment extending from 1489 aa to 1572 aa (IC3.4) was responsible for this binding. This region may have multiple antibody binding sites. Antibody to human IC3.0 and IC3.4 produced in rabbit, resulted in BMZ separation, histologically identical with that observed when normal human conjunctiva was cultured with OCP sera in an human conjunctival organ culture model.

CONCLUSIONS

These observations identify IC3.4 as the antibody binding site for sera of OCP patients and suggest a possible role for it in blister formation. Indirectly it highlights certain important aspects of the structural and functional dynamics of the biology of the hemidesmosomes and basement membranes.

Heat shock protein 47 in renal scarring

Heat shock protein 47 (HSP47) is a collagen-binding protein, thought to play an essential mechanistic role in the assembly and processing of procollagens. HSP47 is increasingly being implicated in the pathogenesis of several human and experimental fibrotic diseases. HSP47 could mediate increased accumulation of collagens in the fibrotic mass, possibly by regulating increased assembly of procollagens. Therefore, modulation of HSP47 might be a valuable tool for manipulation of some fibrotic diseases, including renal scarring

Attenuation of nephrotoxicity by a novel lipid nanosphere (NS-718) incorporating amphotericin B

NS-718, a lipid nanosphere incorporating amphotericin B, is effective against pathogenic fungi and has low toxicity. We compared the toxicity of NS-718 with that of Fungizone (amphotericin B-sodium deoxycholate; D-AmB) in vitro using renal cell cultures and in vivo by biochemical analysis, histopathological study of the kidney and pharmacokinetic study of amphotericin B following intravenous infusion of the formulation in rats. Incubation with NS-718 resulted in significantly less damage of cultured human renal proximal tubular epithelial cells compared with D-AmB. Serum blood urea and creatinine concentrations increased significantly in rats given an iv infusion of D-AmB 3 mg/kg but not in those given the same dose of NS-718. Histopathological examination of the kidney showed tubular necrosis in D-AmB-treated rats but no change in NS-718-treated rats. Amphotericin B concentrations in the kidney in NS-718-treated rats were higher than those in D-AmB-treated rats. Our in vitro and in vivo results suggest that incorporation of amphotericin B into lipid nanospheres of NS-718 attenuates the nephrotoxicity of amphotericin B.

The possible role of colligin/HSP47, a collagen-binding protein, in the pathogenesis of human and experimental fibrotic diseases

Colligin or heat shock protein 47 (HSP47) is a stress protein that resides in the endoplasmic reticulum and is thought to participate in intracellular processing, folding, assembly and secretion of procollagens. Irrespective of the tissue site and organ, induction of colligin/HSP47 expression is always noted during the process of fibrosis, particularly in and around the fibrotic lesions in both humans and experimental models. Its expression is highly tissue- and cell-specific, and restricted to mostly phenotypically altered collagen-producing cells. These observations suggest that upregulation of this collagen-specific chaperone-colligin/HSP47 may play an important role in the subsequent fibrotic process, possibly by regulating increased synthesis/assembly of collagens.

Role of glomerular epithelial cell-derived heat shock protein 47 in experimental lipid nephropathy

BACKGROUND

Heat shock protein 47 (hsp47) is a collagen-specific stress protein and is shown to be involved in the synthesis/assembly of various collagens as a molecular chaperone. This study was undertaken to investigate the possible role of hsp47 in dietary-induced hypercholesterolemic rat kidneys, which showed glomerular hypercellularity with expansion of mesangial matrix.

METHODS

Dietary-induced hypercholesterolemia was induced in male Wistar rats by giving 2% cholesterol diet for four months. Immunohistochemistry was used for localization of protein products for collagens (types I, III, and IV). alpha-smooth muscle actin, vimentin, desmin, and ED-1, a macrophage/monocyte marker, and hsp47 in control and hypercholesterolemic rat kidneys.

RESULTS

Compared with the control, increased accumulation of collagens was accompanied with increased expression of hsp47 in hypercholesterolemic rat kidneys, with predominant expression in the glomeruli. By double immunostaining, desmin-positive glomerular epithelial cells were found to be the main source of hsp47 in hypercholesterolemic rat kidneys.

CONCLUSION

From these results, it is concluded that induced expression of hsp47 by phenotypically altered glomerular epithelial cells might play a role in the excessive assembly/synthesis of collagens and could thereby contribute to the glomerulosclerosis found in dietary-induced hypercholesterolemic rat kidneys.

Cisplatin-induced apoptosis in human proximal tubular epithelial cells is associated with the activation of the Fas/Fas ligand system

The role of Fas and Fas ligand (Fas-L) in the apoptotic cell death process in cisplatin (CP)-treated human proximal tubular epithelial cells (PTECs) was examined. The human PTECs were treated with various concentrations (20-80 microM) of CP for 24 h, and the incidence of apoptosis in CP-treated cells was assessed by trypan blue staining, propidium iodide staining, in situ end labeling, and electron microscopy. The expression of Fas and Fas-L was detected by immunofluorescence microscopy. The results showed that: (1) CP-treatment resulted in a decreased number of live human PTECs and an increased number of dead cells, (2) CP-treated human PTECs showed an increased rate of apoptosis with its typical morphological features, and (3) expression of both Fas and Fas-L was upregulated in CP-treated human PTECs. These results indicate that CP treatment induces apoptosis in human PTECs and the activation of the Fas/Fas-L system may play an active role in the induction of the apoptotic cell death process.

Life-long caloric restriction suppresses age-associated Fas expression in the Fischer 344 rat kidney

It has been shown that the expression of Fas is substantially increased in the aging process in various organs, but its role in the aging kidney is not yet clear. In this study, the expression of Fas in the kidneys of 6- and 24-month-old male Fischer 344 rats fed ad libitum was studied by using quantitative reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry. In addition, possible effects of life-long caloric restriction (30% as those of ad libitum fed group) in the expression of Fas were also studied in 6- and 24-month-old rat kidneys. Kidneys obtained from 24-month-old ad libitum fed rats showed glomerulosclerosis with marked tubulointerstitial damage including interstitial fibrosis, while in the kidneys of 24-month-old calorie-restricted rats, renal damage was remarkedly less than that noted in 24-month-old ad libitum fed rats kidneys. RT-PCR and immunohistochemical analysis showed an increased expression of Fas in both mRNA and protein level in 24-month-old rat kidneys; life-long caloric restriction significantly reduces renal expression of Fas. Our results suggest that increased expression of Fas is associated with age-related renal damage and that life-long diet-restricted alteration of its expression is associated with the modulation of age-associated renal structural damage.

Coadministration of basic fibroblast growth factor and sucrose octasulfate (sucralfate) facilitates the rat dorsal flap survival and viability

The effective use of local growth factors and cytokines may replace the lengthy staged surgical delay process. We tested the efficacy of basic fibroblast growth factor (bFGF) coadministered with sucralfate (sucrose octasulfate) on the rat dorsal flap model. A total of 76 male Wistar rats were used in this experiment. Four groups of the animals were divided. Group 1 (n = 5) was the vehicle control (saline soaked), group 2 (n = 5) was sucrose octasulfate soaked (100 microg/ml, 1 ml), group 3 (n = 5) was bFGF soaked (1 microg/ml, 1 ml), and group 4 (n = 5) was both bFGF and sucrose octasulfate soaked. All agents were soaked equally in Gelfoam. The flap survival measured by the quantitative computer-assisted morphologic analysis was significantly improved by day 5 postoperatively in the combined administration group compared with the vehicle control (81 and 53 percent, respectively; p < 0.05). In lead oxide-gelatin microangiography, there was enhanced pedicle vessel formation observed as well as the extended vessel sprouting up to very close to the distal end in combined group on day 5. The endogenous bFGF mRNA expressions shown by reverse transcriptase-polymerase chain reaction were detected in all four groups. The angiogenesis indicated by alpha-smooth muscle actin immunopositivity was significantly more enhanced in the combined group than the vehicle control (37.3 and 19.4, respectively; p < 0.01). In the combined group, there was stronger immunopositivity for bFGF in epidermis and hair follicles observed, and more notably bFGF-immunopositive dermal fibroblasts were evident. Thus, coadministration of bFGF and sucralfate markedly facilitates the rat dorsal flap survivability by enhancing the bFGF expression and angiogenesis.

Life-long dietary restriction modulates the expression of collagens and collagen-binding heat shock protein 47 in aged Fischer 344 rat kidney

It has been shown that the expression of HSP47 and collagens is substantially increased in the sclerotic/fibrotic process in various organs, including kidney. However, the factors regulating the increased expression of HSP47 are not yet clear. In this study, we examined the effect of dietary restriction for the expression of collagens and collagen-binding HSP47 in the kidneys of 6- and 24-month-old male Fischer 344 (F 344) rats fed ad libitum or 30% diet-restricted. No significant histological alteration was found in the kidneys of 6-month-old fed or diet-restricted rats. Kidneys obtained from 24-month-old freely fed rats showed glomerulosclerosis with marked tubulointerstitial damage including interstitial fibrosis, while in the kidneys of 24-month-old diet-restricted rats, renal damage was remarkably less than those noted in 24-month-old freely fed rat kidneys. Immunohistochemical analysis showed an increased accumulation of type I, type III and type IV collagens in areas of glomerulosclerosis and interstitial fibrosis in old rat kidneys. Dietary restriction significantly reduces renal accumulation of collagens in old age. Aging enhanced expression of HSP47 in 24-month-old freely fed rat kidneys whereas dietary restriction suppressed its expression in 24-month-old diet-restricted rat kidneys. Also, phenotypic alterations of mesangial cells and interstitial cells (immunopositive for alpha-smooth muscle actin), glomerular epithelial cells (immunopositive for desmin) and tubular epithelial cells (immunopositive for vimentin) were seen in 24-month-old freely fed rat kidneys and found to express HSP47. Dietary restriction significantly diminished phenotypically altered renal cells in 24-month-old rat kidneys. Our results suggest that increased expression of HSP47 is associated with age-related renal damage and that diet-restricted alteration of its expression is associated with the modulation of age-associated renal sclerosis/fibrosis.

Localization in situ of type VI collagen protein and its mRNA in mesangial proliferative glomerulonephritis using renal biopsy sections

Extracellular matrix accumulation is crucial in the pathogenesis of glomerulosclerosis in mesangial proliferative glomerulonephritis (GN). In an attempt to explore the distribution of type VI collagen and its synthesizing cells in normal and diseased glomeruli, we investigated mRNA and protein expression of type VI collagen in renal biopsy sections, histologically diagnosed as mesangial proliferative GN. Five renal biopsies from patients diagnosed as having minor glomerular abnormalities and one surgical renal tissue were also simultaneously examined as controls. Immunohistochemical studies revealed type VI collagen immunostaining in the mesangium and glomerular basement membrane of the control glomeruli. Compared to the control, increased deposition of type VI collagen was noted in the mesangial proliferative and sclerotic lesions in GN. To identify the cells responsible for the synthesis of type VI collagen mRNA, renal sections were hybridized in situ with digoxigenin-labeled antisense oligo-DNA probe complementary to a part of alpha1 (VI) mRNA. Occasionally intraglomerular cells hybridized with digoxigenin-labeled antisense pro alpha1 (VI) oligo-DNA in control glomeruli. An increased number of intraglomerular cells (mostly epithelial cells) were, however, positive for alpha1 (VI) mRNA expression in GN sections. The present study documents the distribution of type VI collagen in the normal glomeruli and provides further evidence of accelerated synthesis of this collagen in mesangial proliferative GN.

Coexpression of collagens and collagen-binding heat shock protein 47 in human diabetic nephropathy and IgA nephropathy

The mechanism of structural changes of the kidney in human diabetic nephropathy (DN) and IgA nephropathy (IgAN) is not yet completely known, but excessive deposition of extracellular matrix (ECM), including various collagens, may be crucial to this process. Heat shock protein (HSP) 47 has been identified as collagen-binding stress protein, shown to have a specific role in the intracellular processing of procollagen molecules during collagen assembly. To determine whether increased deposition of collagens in human DN and IgAN is related to HSP47, we investigated the expression of HSP47 in renal biopsy and autopsy sections obtained from 22 DN and 45 IgAN patients. Five renal biopsy specimens, diagnosed as minor glomerular abnormalities, were simultaneously studied as controls. Monoclonal antibodies specific for HSP47, type III collagen and type IV collagen were used to assess the relative expression of their proteins in paraffin-embedded renal sections by immunohistochemistry. Increased deposition of collagens was closely related to the sclerotic activity of the disease process in DN and IgAN; increased deposition of collagens was often present in relation to a strong expression of HSP47, a stress protein known to regulate collagen synthesis/assembly. By double immunostaining, we found colocalization of collagens and their molecular chaperone HSP47 in the sclerotic glomeruli and tubulointerstitium in DN and IgAN. Our results strongly support a pathologic role for HSP47 in both these diseases and that increased levels of HSP47 may play an important role in the excessive assembly of collagens resulting in glomerulosclerosis and interstitial fibrosis found in DN and IgAN patients.

Immunolocalization of collagen and collagen-binding heat shock protein 47 in fibrotic lung diseases

Pulmonary fibrosis resulting from increased accumulation of various extracellular matrices is a prominent feature in chronic progressive lung diseases. Heat shock protein 47 (HSP47) is a collagen-binding stress protein known to have a specific role in the intracellular processing of procollagen molecules as a collagen-specific molecular chaperone in various organs. Possible involvement, however, of HSP47 in relation to increased deposition of collagens in fibrotic lung diseases is not yet known. In this study, we investigated the expression of HSP47 in various pulmonary fibrotic diseases. Formalin-fixed, paraffin-embedded lung sections from 17 autopsies of patients with various pulmonary fibrotic diseases, e.g., organizing pneumonia, interstitial pneumonia, idiopathic pulmonary fibrosis, and diffuse alveolar damage, were stained with monoclonal antibodies for alpha-smooth muscle actin, vimentin, CD68, Type III collagen, and HSP47. The extent of staining was graded semiquantitatively. Five control lung sections were also simultaneously studied. The fibrotic lung sections, in comparison with the control sections, had more interstitial cells positive for alpha-smooth muscle actin and fibroblasts positive for vimentin; we also saw increased infiltration of CD68-positive macrophages. For HSP47, in comparison with the control lung sections, markedly increased immunostaining was always noted in the fibrotic lung sections in association with increased accumulation of Type III collagen in the fibrotic masses. By double immunostaining, colocalization of collagens and HSP47 was noted in the regions of pulmonary fibrosis, and HSP47-expressing cells were found to be mainly alpha-smooth muscle actin-positive interstitial cells. From the above observations, we concluded that overexpression of HSP47 might play an important role in the excessive assembly/synthesis of collagens and could thereby contribute to the fibrosis found in pulmonary fibrotic lung diseases.

Expression of vascular endothelial growth factor and its receptors in rats with protein-overload nephrosis

BACKGROUND

Based on the fact that vascular endothelial growth factor (VEGF) increases vascular permeability, it is speculated that VEGF might be involved in the development of proteinuria, although this remains unconfirmed. The production and site of action of VEGF remains unclear in nephrotic renal diseases.

METHODS

Non-radioactive in situ hybridization was performed to examine the expression of VEGF mRNA and its receptors, flt-1 and KDR/flk-1, in a rat model of nephrosis induced by intraperitoneal injection of bovine serum albumin (BSA). Saline injected rats were served as control animals.

RESULTS

Neither morphological changes nor deposition of immunoglobulin or complement were observed in our model. Proteinuria developed, reaching a maximum level in rats injected with BSA for 3 days, followed by persistent proteinuria until day 14. The expression of mRNA for VEGF and the two receptors was markedly upregulated in glomeruli of BSA-induced nephritis compared with the control group. VEGF mRNA was localized in glomerular cells, including cells in mesangium, visceral and parietal epithelial cells. In contrast, flt-1 mRNA and KDR/flk-1 mRNA were expressed on glomerular endothelial cells and cells in mesangium. The ratio of glomerular cells positive for VEGF mRNA and its receptors mRNA increased proportionately with the severity of proteinuria. Immunohistochemistry for ED-1 and proliferating cell nuclear antigen showed no significant increase in infiltrating macrophage or cellular proliferation.

CONCLUSIONS

Our results suggest that altered glomerular expression of VEGF and its receptors is not associated with proliferation of endothelial cells, but rather with proteinuria in BSA-induced nephritis in rats. VEGF may play a different role in different renal diseases.

Age-related nephropathy in the Fischer 344 rat is associated with overexpression of collagens and collagen-binding heat shock protein 47

To explore the possible role of heat shock protein (HSP) 47 in the age-related renal changes in Fischer 344 (F 344) rats, the expression of collagen-binding HSP47 with various proteins implicated in phenotypic modulation (alpha-smooth muscle actin, desmin, and vimentin) and fibrosis (type I, type III, and type IV collagens) was examined in young and old F 344 rat kidneys. Male F 344 rats often develop spontaneous nephropathy in old age. Kidneys obtained from 24-month-old F 344 rats showed glomerulosclerosis with marked tubulointerstitial damage including interstitial fibrosis, while no significant histological alteration was found in the kidneys of 6-month-old rats. Immunohistochemical analysis showed an increased accumulation of type I, type III, and type IV collagens in areas of glomerulosclerosis and interstitial fibrosis in old rat kidneys. In kidneys of young rats, collagen-binding HSP47 expression was weak in the glomeruli and occasionally seen in the interstitial cells. In contrast, strong immunostaining for HSP47 was noted in the glomeruli, tubular epithelial cells, and interstitial cells in kidneys of old rats. In addition, phenotypic alterations of mesangial cells and interstitial cells (immunopositive for alpha-smooth muscle actin), glomerular epithelial cells (immunopositive for desmin), and tubular epithelial cells (immunopositive for vimentin) were found in the kidneys of old F 344 rats. Double immunostaining showed that all these phenotypically altered renal cells express HSP47 and that increased expression of HSP47 was always associated with increased expression of collagens in the old rat kidneys. From the above observations, it is concluded that overexpression of HSP47 by phenotypically altered renal cells might play an important role in the excessive assembly of collagens and could thereby contribute to the glomerulosclerosis and interstitial fibrosis found in kidneys of aged F 344 rats.

Bleomycin-induced pulmonary fibrosis in rat is associated with increased expression of collagen-binding heat shock protein (HSP) 47

Increased accumulation of collagens in extracellular matrix (ECM) is mainly responsible for bleomycin-induced pulmonary fibrosis in rats. This study was designed to assess whether increased collagen accumulation in bleomycin-induced pulmonary fibrosis is associated with heat shock protein (HSP) 47, a molecular chaperone for collagen biosynthesis. We investigated the expression of type I and type III collagens and HSP47 in bleomycin-induced pulmonary fibrosis. Fifteen male Wistar rats were divided into two groups; group I: bleomycin-induced pulmonary fibrosis; group II: PBS-treated age-matched control rats. Pulmonary fibrosis was induced by injecting a single dose of bleomycin sulphate (5 U/kg body weight) intratracheally. Three bleomycin-treated rats and two age-matched control rats were sacrificed at the end of each of the 1st, 2nd and 4th weeks of the experiment. In bleomycin-treated rats, histological examination revealed pulmonary fibrosis, which increased with time. Increased type I and type III collagen desposition was observed in the lungs of all the bleomycin-treated rats. Weak immunostaining of HSP47 was noted in the control lungs. In contrast, strong immunostaining for HSP47 was seen in all the bleomycin-treated fibrotic lungs. In addition, increased numbers of phenotypically altered myofibroblasts (alpha-smooth muscle actin immunopositive) and fibroblast (vimentin immunopositive) were seen in bleomycin-treated lungs and found to express HSP47. Parallel increase of collagens and their molecular chaperone HSP47 expression was found in the bleomycin-treated lungs, and their co-localization could be detected by double immunostaining. Overexpression of HSP47 may play a significant part in the excessive assembly of collagens and could contribute in this way to the fibrosis found in bleomycin-treated rat lungs.

[A case of systemic lupus erythematosus associated with minimal change nephrotic syndrome]

A case of systemic lupus erythematosus (SLE) associated with minimal change nephrotic syndrome (MCNS) in a 25-year-old female is described. The patient suddenly manifested butterfly rash and proteinuria was first pointed out on March, 1994. On admission, her skin biopsy indicated SLE. Subsequently, she developed nephrotic syndrome. Urinalysis showed heavy proteinuria (4.1 g/day), with no other abnormalities in the urinary sediment. Immunological examination revealed positive antinuclear antibody at a titer of 1:80 with a speckled pattern. Anti-ssDNA and anti-SS-A antibodies were positive, but other antibodies were negative. Serum complement (CH50) was within the normal range (30.5 U/ml). The renal biopsy showed no apparent cellular proliferation or increase of extracellular matrices in glomeruli by light microscopy. Slight deposition of IgG, IgM, C3 and C1q was focally seen in the mesangium and capillary wall by immunofluorescence. Electron microscopic examination revealed small and scattered dense deposits in the mesangium, subepithelium and subendothelium, associated with diffuse fusion of the foot processes of epithelial cells along the glomerular basement membrane. According to the WHO classification, the histological features were compatible with those of lupus nephritis (LN), class Ib. The patient was treated with PREDNISOLONE, Mizorbine and Dilazep, resulting in the disappearance of proteinuria and a normal serum level of total protein. The association of LN and MCNS is very rare. We also investigated the relationship between the intensity of proteinuria and histological types of 53 cases with LN examined in our laboratory. The cases with heavy proteinuria were mostly classified as WHO-Class IV and Class V. We report here a case of LN associated with MCNS and also review the literatures.

Collagen-binding heat shock protein (HSP) 47 expression in anti-thymocyte serum (ATS)-induced glomerulonephritis

An increased accumulation of extracellular matrix (ECM), predominantly collagens, is the main component of the expanded mesangial matrix in anti-thymocyte serum (ATS)-induced glomerulonephritis (GN). Heat shock protein (HSP) 47 is a collagen-binding stress protein and has been shown to have a specific role in the intracellular processing of procollagen molecules. It is a collagen-specific molecular chaperone in various organs, but its role in the kidney in relation to matrix expansion is not yet known. This study was designed to assess whether increased ECM accumulation in ATS-induced GN is associated with HSP47. The expression of type I, type III and type IV collagens, with their molecular chaperone HSP47, was investigated in ATS-induced GN rat kidneys. Fifteen male Wistar rats were divided into two groups: ATS-induced GN rats (group I) and age-matched controls (group II). GN was induced by injecting a single dose of ATS (0.8 ml/100 g body weight). All the rats were killed on the third and tenth day of the experiment. In group I, 3 days after ATS injection, histological examination revealed a reduction in glomerular cell number with mesangiolysis. However, 10 days after ATS injection, histologically severe mesangial cell proliferation with expansion of the mesangial matrix was noted in group I rats. By semiquantitative analysis, compared with controls, increased type I, type III, and type IV collagen immunostaining was observed in the expanded mesangial matrix in ATS-induced GN (group I) rats on day 10. Immunoreactive HSP47 expression was weak in the intraglomerular cells and was occasionally seen in the interstitial cells in control kidneys. In contrast, strong immunostaining for HSP47 was noted in the glomeruli of the ATS-treated rat kidneys on day 10. In this study, there was a parallel increase of various collagens and their molecular chaperone HSP47 in the ATS-treated rat kidneys. Compared with controls, no significant difference in HSP47 expression was found in the ATS-treated rat kidneys without mesangial matrix expansion (3 days after ATS injection). It is concluded that overexpression of HSP47 might play a significant role in the excessive assembly of collagens and could subsequently contribute to the expansion of mesangial matrix found in ATS-treated rat kidneys.

Identification of type VI collagen synthesizing cells in human diabetic glomerulosclerosis using renal biopsy sections

Although the role of extracellular matrices in the development of glomerulosclerosis has been discussed widely, the cellular origin of type VI collagen in diabetic nephropathy (DN) has remained relatively unexplored. This study reports the distribution and cellular origin of type VI collagen in DN. Type VI collagen-specific oligonucleotide probes and monoclonal antibody were used to assess the relative expression of mRNA for alpha 1 (VI) chain and its translated protein in paraffin-embedded renal biopsy sections of DN. By immunohistochemistry, compared to the control, increased deposition of type VI collagen was noted in the diffuse and nodular lesions of diabetic glomeruli. For cellular localization of type VI collagen mRNA, paraffin-embedded renal sections of the control and DN were hybridized in situ with digoxigenin (Dig)-labeled antisense oligo-DNA probe complementary to a part of alpha 1 (VI) mRNA. In comparison to the control kidney sections, increased numbers of intraglomerular cells (both mesangial and epithelial cells) were positive for alpha 1 (VI) mRNA in renal biopsy sections of DN. From the results, we conclude that overexpression of type VI collagen by intraglomerular cells with its increased deposition might significantly contribute to the glomerulosclerosis found in DN.

Significance of increased accumulation of type VI collagen and transforming growth factor beta 1 in tubulointerstitial damage in hypertensive nephrosclerosis: an immunohistochemical study

The distribution of type VI collagen and transforming growth factor beta 1 (TGF beta 1) was studied by immunohistochemistry in 12 renal biopsy specimens of hypertensive nephrosclerosis and five control cases. In control kidneys, the immunostaining of type VI collagen was found in the mesangium, glomerular basement membrane and tubular basement membrane. For TGF beta 1, mesangium, glomerular basement membrane, tubular basement membrane and tubular epithelial cells stained positively in the control kidneys. In contrast to the control cases, markedly increased immunostaining for both type VI collagen and TGF beta 1 was consistently observed in tubulointerstitial damage in hypertensive nephrosclerosis. These immunohistochemical findings provide the evidence for a parallel increase of both type VI collagen and TGF beta 1 during the process of tubulointerstitial injury in hypertensive nephrosclerosis. From the results of the present study, it is speculated that TGF beta 1 may contribute to the tubulointerstitial injury by stimulating increased synthesis of various extracellular matrix including type VI collagen.

Trapidil modifies mesangial cell proliferation and collagen accumulation in anti-thymocyte serum (ATS)-induced glomerulonephritis

This study was designed to assess whether the glomerular mesangial-cell proliferation and the increased extracellular matrix (ECM) accumulation that occur in anti-thymocyte serum (ATS)-induced glomerulonephritis (GN) are affected by Trapidil, a potent antagonist for platelet-derived growth factor (PDGF). Fifteen male Wistar rats were divided into three groups. In group I, GN was induced by injecting a single dose of ATS. In group II, rats were given a single dose of ATS followed by daily treatment with Trapidil. In group III, the rats (controls) were treated with a single dose of phosphate buffered saline. All the rats were killed on the 10th day of the experiment. ATS induced marked mesangial cell proliferation (P < 0.01) in group I rats and Trapidil treatment (group II) significantly suppressed such proliferation (P < 0.01). Increased type III and IV collagen immunolabelling was observed in the expanded mesangial matrix in group I rats. In group II, immunolabelling for type III and IV collagen was much less than in group I. The study suggests that Trapidil therapy is effective in suppressing both mesangial cell proliferation and mesangial matrix expansion by reducing collagen accumulation.

Immunohistochemical analysis of type III and IV collagens in tubulointerstitial damage in human benign nephrosclerosis

Prolonged hypertension causes structural changes including glomerulosclerosis and tubulointerstitial damage of the kidney, termed benign nephrosclerosis. It is generally accepted that, in benign nephrosclerosis, increased accumulation of extracellular matrix in the glomeruli results in glomerulosclerosis. Little is known, however, about the possible role of the extracellular matrix in the tubulointerstitial damage in benign nephrosclerosis. In this study, the possible roles of type IV basement-membrane collagen and type III interstitial collagen in tubulointerstitial damage caused by hypertension were explored. Immunohistochemical techniques were used to investigate the distribution of type III and type IV collagens in the kidney sections of 15 patients with benign nephrosclerosis with tubulointerstitial damage and in 10 controls. In the control renal sections strong immunostaining for type III collagen was found in the interstitium and immunostaining for type IV collagen was present in the tubular basement membrane and weakly in the interstitium. In the patients with tubulointerstitial damage there was increased immunostaining for both type III and type IV collagens in the expanded interstitium and damaged tubules than was found in the control kidney sections. These findings indicate that increased accumulation of both type III and type IV collagens might play a significant role in the tubulointerstitial damage in benign nephrosclerosis.

Suppression of mesangial-cell proliferation by trapidil in glomerulonephritis induced by anti-thymocyte serum in rats

Trapadil (Mochida Pharmaceuticals, Japan), an antiplatelet drug, suppresses the growth of several cell types and is thought to antagonize platelet-derived growth factor. The effects of trapidil on mesangial-cell proliferation in glomerulonephritis induced by anti-thymocyte serum in Wistar rats were investigated. Control rats were treated with phosphate-buffered saline (group I); group II rats were injected with a single dose of anti-thymocyte serum (8 ml/kg body weight), and group III rats were treated with both a single dose of anti-thymocyte serum (8 ml/kg body weight) and with trapidil (5 mg/kg body weight/day). Three rats in each group were killed on day 3, and the other three on day 10. Control rats showed no significant histological changes on day 3 or day 10. In group II, on day 3, there was a marked decrease in glomerular cell numbers, with mesangiolysis. Histologically severe mesangial-cell proliferation with expansion of mesangial areas was noted on day 10. None of the rats in group III showed mesangial alterations, histologically, indicating that mesangial-cell proliferation was suppressed by trapidil. This suppression may result from antagonism of the binding of platelet-derived growth factor to the specific surface receptors in the mesangial cells. Trapidil may have clinical value in the treatment of mesangial-cell proliferative glomerular diseases.

Synthesis of type III collagen and type IV collagen by tubular epithelial cells in diabetic nephropathy

Overproduction of extracellular matrix (ECM) is considered to be primarily responsible for both glomerular and tubulointerstitial (TI) changes in diabetic nephropathy (DN). To clarify the possible role of the collagens in TI damage in DN, type III interstitial collagen and type IV basement membrane collagen were studied in 10 cases of DN and 10 control cases by immunohistochemistry and in situ hybridization techniques. In control cases, no immunostaining for type III collagen was found in the renal tubules, while strongly positive in the adjacent interstitium. On the other hand, type IV collagen was found weakly in the tubular basement membrane (TBM) in control cases. In DN, increased immunostaining for both type III and type IV collagens were found in the damaged tubulointenstitium (TI). To determine the sources of these collagens in TI damage, non-radioactive in situ hybridization was performed utilizing thymine-thymine (T-T) dimerized synthetic oligonucleotides complementary to either human pro alpha 1 (III) chain or pro alpha 1 (IV) chain mRNA as probe. In normal tubules, tubular epithelial cells were not uniformly but persistently positive for pro alpha 1 (IV) mRNA. Meanwhile, no specifically detectable positive hybridization signals for pro alpha 1 (III) mRNA was found in the normal tubular epithelial cells. Accelerated synthesis of both type III and type IV collagens by tubular epithelial cells was noted in TI damage in DN. From the results we concluded that excessive synthesis of both type III and type IV collagens by tubular epithelial cells might significantly contribute to the TI damage found in DN.

In situ localization of type III and type IV collagen-expressing cells in human diabetic nephropathy

Nodular intercapillary glomerulosclerosis is the most typical lesion of diabetic nephropathy (DN) and is characterized by increased extracellular matrix (ECM) and amorphous masses of mesangial matrix. The local exaggeration of these deposits results in the formation of the typical diabetic nodule. To clarify the composition of the ECM of sclerotic lesions in DN, we investigated the distribution of type III and type IV collagens and their mRNAs by immunohistochemistry and in situ hybridization, respectively. In normal renal tissues, there was no intraglomerular immunostaining for type III collagen, while strongly positive staining was found in the extraglomerular interstitium. Positive immunostaining for type IV collagen was also present in the mesangium, glomerular basement membrane (GBM), Bowman's capsule, and the vascular pole of the normal glomerulus. In DN, the nodular lesions were negative for type III collagen and strongly positive for type IV collagen. On the other hand, in the late stage of global sclerosis, both type III and type IV collagens were diffusely present in the sclerotic matrix. To determine the origins of these type III and type IV collagens in the sclerotic matrix, in situ hybridization was performed, utilizing thymine-thymine (T-T) dimerized synthetic oligonucleotides complementary to either pro alpha 1(III) chain or pro alpha 1(IV) chain mRNAs as probes. The signals were detected by enzyme immunohistochemistry using an anti-T-T antibody. Intraglomerular cells (glomerular epithelial and mesangial cells) containing type III collagen mRNA were found in DN with sclerotic lesions, but not in normal glomeruli.(ABSTRACT TRUNCATED AT 250 WORDS)

Glomerular expression of type III and type IV collagens in benign nephrosclerosis: immunohistochemical and in situ hybridization study

The development of glomerular sclerosis in benign nephrosclerosis (BNS) was studied. We investigated the intraglomerular expression of type III and IV collagens and their mRNAs by immunohistochemistry and by the in situ hybridization method. Formalin-fixed paraffin sections from 28 patients with BNS and 10 control cases were stained by the avidin-biotin complex (ABC) method using monoclonal antibodies for human type III and IV collagens. In the course of the sclerotic process of the glomerulus in BNS, the glomerular staining intensity of type IV collagen increased. The strongest staining was observed in the glomerulus at the early sclerotic stage, and intensity decreased slightly at the later stages. Although type III collagen was absent in normal and nonsclerotic glomeruli, peripheral regions of the sclerotic glomeruli were positive at the early sclerotic stage. Later, type III collagen was diffusely observed in the completely hyalinized glomeruli. The expression of type III and type IV collagen mRNAs was detected in the glomeruli of BNS by the non-radioactive in situ hybridization method using thymine-thymine (T-T) dimerized synthetic oligonucleotides. The number of mRNA positive cells for type III and type IV collagens increased at the presclerotic and early sclerotic stages. But these cells gradually decreased in number as glomerular sclerosis developed. We concluded that type III collagen was presumably synthesized by the intraglomerular cells and may contribute to the development of glomerular sclerosis in BNS along with type IV collagen.