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

The Synthesis and Biological Applications of the 1,2,3-Dithiazole Scaffold

The 1,2,3-dithiazole is an underappreciated scaffold in medicinal chemistry despite possessing a wide variety of nascent pharmacological activities. The scaffold has a potential wealth of opportunities within these activities and further afield. The 1,2,3-dithiazole scaffold has already been reported as an antifungal, herbicide, antibacterial, anticancer agent, antiviral, antifibrotic, and is a melanin and Arabidopsis gibberellin 2-oxidase inhibitor. These structure activity relationships are discussed in detail, along with insights and future directions. The review also highlights selected synthetic strategies developed towards the 1,2,3-dithiazole scaffold, how these are integrated to accessibility of chemical space, and to the prism of current and future biological activities.

Inflammation, oxidative stress and altered heat shock response in type 2 diabetes: the basis for new pharmacological and non-pharmacological interventions

Type 2 diabetes mellitus (DM2) is a chronic disease characterised by variable degrees of insulin resistance and impaired insulin secretion. Besides, several pieces of evidence have shown that chronic inflammation, oxidative stress, and 70 kDa heat shock proteins (HSP70) are strongly involved in DM2 and its complications, and various pharmacological and non-pharmacological treatment alternatives act in these processes/molecules to modulate them and ameliorate the disease. Besides, uncontrolled hyperglycaemia is related to several complications as diabetic retinopathy, neuropathy and hepatic, renal and cardiac complications. In this review, we address discuss the involvement of different inflammatory and pro-oxidant pathways related to DM2, and we described molecular targets modulated by therapeutics currently available to treat DM2.

Anti-HSP47 siRNA lipid nanoparticle ND-L02-s0201 reverses interstitial pulmonary fibrosis in preclinical rat models

ND-L02-s0201 is a lipid nanoparticle encapsulating an siRNA which inhibits expression of heat shock protein 47 (HSP47), a collagen-specific chaperone. Accumulated evidence demonstrates a close association between increased level of HSP47 and excessive accumulation of collagen in fibrotic diseases. Our objective was to test ND-L02-s0201 efficacy in preclinical lung fibrosis models and characterise the downstream histological and functional consequences of inhibiting the expression of HSP47. Comprehensive optimisation and characterisation of bleomycin (BLM) and silica-induced rat lung fibrosis models were conducted, which ensured progressive pathological changes were sustained throughout the study during evaluation of the anti-fibrotic potential of ND-L02-s0201. In the BLM model, we demonstrated dose-dependent and statistically significant reduction in the relative lung weight, collagen deposition and histology, and fibrosis scores following ND-L02-s0201 treatment. Lung tissue mRNA profiling demonstrated that 11 out of 84 fibrosis-relevant genes were upregulated following BLM induction and were downregulated by approximately 4.5-fold following ND-L02-s0201 treatment. Epithelial-mesenchymal transition was characterised in the BLM model following ND-L02-s0201 treatment. Cell enrichment demonstrated that myofibroblasts contained the highest HSP47 mRNA expression. BLM led to more than a five-fold increase in myofibroblasts and ND-L02-s0201 treatment reduced the myofibroblasts to sham levels. Statistically significant improvement in lung function was noted in the BLM model which was determined by running endurance capacity using a 7-minute treadmill test. Comparable anti-fibrotic efficacy was also observed in the silica model. Results from two robust chronic rodent models of pulmonary fibrosis demonstrated significant anti-fibrotic effects and improved lung function which support the evaluation of ND-L02-s0201 in subjects with idiopathic pulmonary fibrosis.

Enhanced Expression of Heat Shock Protein 47 in Rat Model of Peritoneal Fibrosis

← Objective

Peritoneal fibrosis is one of the serious complications of continuous ambulatory peritoneal dialysis therapy and is characterized by collagen accumulation. Heat shock protein 47 (HSP-47) is a collagen-specific molecular chaperon and is closely associated with collagen synthesis; however, the involvement of HSP-47 in the progression of peritoneal fibrosis is not fully understood.

← Design

To examine the serial pathological alterations caused by peritoneal fibrosis, we made an experimental model of peritoneal fibrosis by daily intraperitoneal injection of chlorhexidine gluconate (CG) in rats for 28 days and examined the expression of HSP-47 together with that of types I and III collagen, alpha-smooth muscle actin (αSMA), and ED-1 (a marker for macrophages) using immunohistochemistry. Rats treated with saline containing 15% ethanol were used as the control group.

← Results

In the control group, the peritoneal tissue was slightly thickened and HSP-47 was expressed in the peritoneum at day 28. In the CG group, the peritoneal tissue serially became thickened and fibrotic. The expression of HSP-47 was evident in mesothelial cells and submesothelial connective tissue after day 7 of treatment with CG, and increased thereafter. The expression of types I and III collagen and αSMA was proportionally strengthened during our experiments. ED-1–positive cells were present in thickened areas with abundant proliferation of collagen fiber. The number of cells positive for ED-1 increased gradually and reached a maximum at day 21.

← Conclusion

Our results indicate that, in a rat experimental model of peritoneal fibrosis, the expression of HSP-47 is associated with the progression of peritoneal fibrosis.

Heat Shock Proteins in Vascular Diabetic Complications: Review and Future Perspective

Heat shock proteins (HSPs) are a large family of proteins highly conserved throughout evolution because of their unique cytoprotective properties. Besides assisting protein refolding and regulating proteostasis under stressful conditions, HSPs also play an important role in protecting cells from oxidative stress, inflammation, and apoptosis. Therefore, HSPs are crucial in counteracting the deleterious effects of hyperglycemia in target organs of diabetes vascular complications. Changes in HSP expression have been demonstrated in diabetic complications and functionally related to hyperglycemia-induced cell injury. Moreover, associations between diabetic complications and altered circulating levels of both HSPs and anti-HSPs have been shown in clinical studies. HSPs thus represent an exciting therapeutic opportunity and might also be valuable as clinical biomarkers. However, this field of research is still in its infancy and further studies in both experimental diabetes and humans are required to gain a full understanding of HSP relevance. In this review, we summarize current knowledge and discuss future perspective.

Murine Precision-Cut Kidney Slices as an ex vivo Model to Evaluate the Role of Transforming Growth Factor-β1 Signaling in the Onset of Renal Fibrosis

Renal fibrosis is characterized by progressive accumulation of extracellular matrix (ECM) proteins, resulting in loss of organ function and eventually requiring renal replacement therapy. Unfortunately, no efficacious treatment options are available to halt renal fibrosis and translational models to test pharmacological agents are not always representative. Here, we evaluated murine precision-cut kidney slices (mPCKS) as a promising ex vivo model of renal fibrosis in which pathophysiology as well as therapeutics can be studied. Unique to this model is the use of rodent as well as human renal tissue, further closing the gap between animal models and clinical trials. Kidneys from C57BL/6 mice were used to prepare mPCKS and slices were incubated up to 96h. Viability, morphology, gene expression of fibrosis markers (Col1a1, Acta2, Serpinh1, Fn1, and Pai-1), inflammatory markers (Il1b, Il6, Cxcl1), and protein expression (collagen type 1, α-smooth muscle actin, HSP47) were determined. Furthermore, to understand the role of the transforming-growth factor β (TGF-β) pathway in mPCKS, slices were incubated with a TGF-β receptor inhibitor (LY2109761) for 48 h. Firstly, viability and morphology revealed an optimal incubation period of 48 h. Secondly, we demonstrated an early inflammatory response in mPCKS, which was accompanied by subsequent spontaneous fibrogenesis. Finally, LY2109761 showed great antifibrotic capacity in mPCKS by decreasing fibrosis markers on mRNA level as well as by reducing HSP47 protein expression. To conclude, we here present an ex vivo model of renal fibrosis, which can be used to further unravel the mechanisms of renal fibrogenesis and to screen antifibrotic therapy efficacy.

Heat shock proteins and kidney disease: perspectives of HSP therapy

Heat shock proteins (HSPs) mediate a diverse range of cellular functions, prominently including folding and regulatory processes of cellular repair. A major property of these remarkable proteins, dependent on intracellular or extracellular location, is their capacity for immunoregulation that optimizes immune activity while avoiding hyperactivated inflammation. In this review, recent investigations are described, which examine roles of HSPs in protection of kidney tissue from various traumatic influences and demonstrate their potential for clinical management of nephritic disease. The HSP70 class is particularly attractive in this respect due to its multiple protective effects. The review also summarizes current understanding of HSP bioactivity in the pathophysiology of various kidney diseases, including acute kidney injury, diabetic nephropathy, chronic glomerulonephritis, and lupus nephritis-along with other promising strategies for their remediation, such as DNA vaccination.

Novel immunohistochemical markers differentiate intrahepatic cholangiocarcinoma from benign bile duct lesions

AIMS

The distinction between intrahepatic cholangiocarcinoma (ICC) and benign bile duct lesions can be challenging. Using our previously identified potential biomarkers for ICC, we examined whether these are useful for the differential diagnosis of ICC, bile duct adenoma and reactive bile duct proliferations in an immunohistochemical approach and identified a diagnostic marker panel including known biomarkers.

METHODS

Subjects included samples from 77 patients with ICC, 33 patients with bile duct adenoma and 47 patients with ductular reactions in liver cirrhosis. Our previously identified biomarkers (stress-induced phosphoprotein 1 (STIP1), SerpinH1, 14-3-3Sigma) were tested immunohistochemically following comparison with candidates from the literature (cluster of differentiation 56, heat shock protein (HSP)27, HSP70, B-cell-lymphoma2, p53, ki67).

RESULTS

The expression of SerpinH1 and 14-3-3Sigma was significantly higher in ICC than in bile duct adenomas and ductular reactions (p<0.05), whereas STIP1 expression was significantly higher (p<0.05) in ICC than in ductular reactions, but the difference to the bile duct adenoma group was not significant. A panel of the biomarker SerpinH1, 14-3-3Sigma and ki67 (≥2 marker positive) showed a high diagnostic accuracy (sensitivity 87.8%, specificity 95.9%, accuracy 91.8%) in the differential diagnosis of ICC versus non-malignant bile duct lesions.

CONCLUSIONS

This suggests that 14-3-3Sigma and SerpinH1 may be useful in the differential diagnosis of malignant, benign and reactive bile duct lesions in addition to ki67 where a cut-off of >5% might be used for the distinction of malignant and non-malignant lesions.

Influence of gentamicin-coded PVDF suture material on the healing of intestinal anastomosis in a rat model

PURPOSE

Intestinal anastomosis is a fundamental procedure in general surgery and required to restore intestinal continuity following resection. The aim of this study was to evaluate whether a gentamicin-coated polyvinylidene fluoride (PVDF) suture material has beneficial effect on anastomotic healing.

METHODS

Ninety Sprague-Dawley rats were divided into three groups: a PVDF-suture group, a gentamicin-coated PVDF (GPVDF)-suture group and a control group using Maxon® (polyglycolid-co-trimethylene carbonate). For each animal, a colonic anastomosis was performed. Ten animals from each group were sacrificed on postoperative days 3, 5, and 14. Measurements of anastomotic bursting pressure were performed on days 3 and 5. At each time, collagen type I/III ratio, MMP 2 and MMP-9 expression and the proliferation index (Ki67) were analyzed.

RESULTS

In total, 90 animals underwent surgery without postoperative complications. Bursting strength in the GPVDF group was significantly elevated on day 5. Immunohistochemistry showed significant increase of the collagen type I/III ratio for PVDF and GPVDF on days 3 and 5. MMP2 was significantly increased for PVDF on days 3 and 5 and for GPVDF on day 5. The analysis of MMP9 revealed significant increase compared to control on day 3 and 5 (GPVDF) as well as on day 5 (PVDF). Staining for Ki67 revealed a significant elevation on postoperative day 3 for the PVDF and the GPVDF group.

CONCLUSIONS

The present data shows the feasibility of PVDF as suture material for colonic anastomosis and confirms the ability of gentamicin to increase the stability of colonic anastomosis when used as coating material.

Identification of novel biomarker candidates for the immunohistochemical diagnosis of cholangiocellular carcinoma

The aim of this study was the identification of novel biomarker candidates for the diagnosis of cholangiocellular carcinoma (CCC) and its immunohistochemical differentiation from benign liver and bile duct cells. CCC is a primary cancer that arises from the epithelial cells of bile ducts and is characterized by high mortality rates due to its late clinical presentation and limited treatment options. Tumorous tissue and adjacent non-tumorous liver tissue from eight CCC patients were analyzed by means of two-dimensional differential in-gel electrophoresis and mass-spectrometry-based label-free proteomics. After data analysis and statistical evaluation of the proteins found to be differentially regulated between the two experimental groups (fold change ≥ 1.5; p value ≤ 0.05), 14 candidate proteins were chosen for determination of the cell-type-specific expression profile via immunohistochemistry in a cohort of 14 patients. This confirmed the significant up-regulation of serpin H1, 14-3-3 protein sigma, and stress-induced phosphoprotein 1 in tumorous cholangiocytes relative to normal hepatocytes and non-tumorous cholangiocytes, whereas some proteins were detectable specifically in hepatocytes. Because stress-induced phosphoprotein 1 exhibited both sensitivity and specificity of 100%, an immunohistochemical verification examining tissue sections of 60 CCC patients was performed. This resulted in a specificity of 98% and a sensitivity of 64%. We therefore conclude that this protein should be considered as a potential diagnostic biomarker for CCC in an immunohistochemical application, possibly in combination with other candidates from this study in the form of a biomarker panel. This could improve the differential diagnosis of CCC and benign bile duct diseases, as well as metastatic malignancies in the liver.

Role of CXCR1 (CKR-1) in inflammation of experimental mesangioproliferative glomerulonephritis

CXCR1 (CKR-1), a receptor of IL-8, is expressed in various cells including neutrophils and monocytes, both of which play a major role in proliferating glomerular diseases. We investigated time-dependent expression of CXCR1 and the effect of single-dose cyclosporine A (CsA) treatment on this expression in experimental mesangioproliferative glomerulonephritis induced by anti-thymocyte serum (ATS). Wistar rats were divided into three groups. Group 1 (control, n = 24) received non-immune serum. Group 2 (nephritis, n = 24) received ATS. Group 3 (nephritis + CsA, n = 24) received ATS and CsA concomitantly. Kidneys from six rats in each group were removed at sixth hour, 3 days, 5 days, and 7 days. ATS induced proteinuria compared to controls (p < 0.001) and CsA precluded the development of proteinuria. Glomerular inflammation and mesangial proliferation were significantly higher in ATS group than control and CsA-treated rats (p < 0.001). ATS injection caused marked interstitial inflammation that was precluded by CsA (p < 0.001). CXCR1 was not expressed in control kidneys. However, ATS induced expression of CXCR1 in both glomeruli and tubulointerstitium. CsA treatment precluded CXCR1 expression in both glomeruli and tubulointerstitium only in the first 6 h. CXCR1 may contribute to inflammation in experimental mesangioproliferative glomerulonephritis. CsA may be beneficial by inhibiting CXCR1 expression and corresponding inflammation.

Epithelial phenotypic changes are associated with a tubular active fibrogenic process in human renal grafts

Some recently published works contest the epithelial origin of myofibroblasts, which are the major extracellular matrix producers. However, our previous studies showed that, in tubular cells, some phenotypic changes reminiscent of epithelial-to-mesenchymal transition constitute an interesting early marker that predicts the progression of fibrosis in renal grafts. We hypothesized that activated epithelial cells could directly contribute to fibrogenesis, although they remain within the tubules. Using immunohistochemistry, we studied the association between epithelial phenotypic changes (de novo expression of vimentin and intracellular translocation of β-catenin) and the production of profibrotic molecules (connective tissue growth factor, HSP47, and laminin), in tubular epithelial cells from 93 renal grafts biopsied of 77 patients. We observed the de novo production of connective tissue growth factor, HSP47, and laminin in the tubular epithelial cells displaying epithelial phenotypic changes. The score of vimentin was significantly correlated with those of connective tissue growth factor (r = 0.785, P < .0001), HSP47 (r = 0.887, P < .0001), and laminin (r = 0.836, P < .0001). The level of tubular expression of mesenchymal cell markers and profibrogenic molecules, but not graft histologic lesions according to Banff acute or chronic scores, was correlated with graft dysfunction and proteinuria at the time of biopsy (r = -0.611, P < .0001 for vimentin with estimated glomerular filtration rate) (r = 0.42, P = .0006 for vimentin with proteinuria). Our results demonstrate that the epithelial phenotypic switch is associated with an active fibrogenic process in tubular epithelial cells and with graft injury indicators. Perpetuation of this tissue injury-repair response may drive fibrogenesis in renal grafts. This "repair response" represents an interesting marker for renal graft surveillance.

HSP47 regulates ECM accumulation in renal proximal tubular cells induced by TGF-β1 through ERK1/2 and JNK MAPK pathways

Heat shock protein (HSP)47 is a collagen-specific molecular chaperone that is essential for the biosynthesis of collagen molecules. It is likely that increased levels of HSP47 contribute to the assembly of procollagen and thereby cause an excessive accumulation of collagens in disease processes associated with fibrosis. Although HSP47 promotes renal fibrosis, the underlying mechanism and associated signaling events have not been clearly delineated. We examined the role of HSP47 in renal fibrosis using a rat unilateral ureteral obstruction model and transforming growth factor (TGF)-β(1)-treated human proximal tubular epithelial (HK-2) cells. An upregulation of HSP47 in both in vivo and in vitro models was observed, which correlated with the increased synthesis of extracellular matrix (ECM) proteins and expression of tissue-type plasminogen activator inhibitor (PAI)-1. Blockade of HSP47 by short interfering RNA suppressed the expression of ECM proteins and PAI-1. In addition, TGF-β(1)-induced HSP47 expression in HK-2 cells was attenuated by ERK1/2 and JNK MAPK inhibitors. These data suggest that ERK1/2 and JNK signaling events are involved in modulating the expression of HSP47, the chaperoning effect of which on TGF-β(1) would ultimately contribute to renal fibrosis by enhancing the synthesis and deposition of ECM proteins.

Genetic induction of phosphate toxicity significantly reduces the survival of hypercholesterolemic obese mice

OBJECTIVE

The adverse effects of metabolic disorders in obesity have been extensively studied; however, the pathologic effects of hyperphosphatemia or phosphate toxicity in obesity have not been studied in similar depth and detail, chiefly because such an association is thought to be uncommon. Studies have established that the incidence of obesity-associated nephropathy is increasing. Because hyperphosphatemia is a major consequence of renal impairment, this study determines the in vivo effects of hyperphosphatemia in obesity.

METHODS AND RESULTS

We genetically induced hyperphosphatemia in leptin-deficient obese (ob/ob) mice by generating ob/ob and klotho double knockout [ob/ob-klotho(-/-)] mice. As a control, we made ob/ob mice with hypophosphatemia by generating ob/ob and 1-alpha hydroxylase double knockout [ob/ob-1α(OH)ase(-/-)] mice. Compared to the wild-type mice, all three obese background mice, namely ob/ob, ob/ob-klotho(-/-), and ob/ob-1α(OH)ase(-/-) mice developed hypercholesterolemia. In addition, the hyperphosphatemic, ob/ob-klotho(-/-) genetic background induced generalized tissue atrophy and widespread soft-tissue and vascular calcifications, which led to a shorter lifespan; no such changes were observed in the hypophosphatemic, ob/ob-1α(OH)ase(-/-) mice. Significantly, in contrast to the reduced survival of the ob/ob-klotho(-/-) mice, lowering serum phosphate levels in ob/ob-1α(OH)ase(-/-) mice showed no such compromised survival, despite both mice being hypercholesterolemic.

CONCLUSION

These genetic manipulation studies suggest phosphate toxicity is an important risk factor in obesity that can adversely affect survival.

Turkistani K, Razzaque MS. Heat shock protein 47: a novel biomarker of phenotypically altered collagen-producing cells

Heat shock protein 47 (HSP47) is a collagen-specific molecular chaperone that helps the molecular maturation of various types of collagens. A close association between increased expression of HSP47 and the excessive accumulation of collagens is found in various human and experimental fibrotic diseases. Increased levels of HSP47 in fibrotic diseases are thought to assist in the increased assembly of procollagen, and thereby contribute to the excessive deposition of collagens in fibrotic areas. Currently, there is not a good universal histological marker to identify collagen-producing cells. Identifying phenotypically altered collagen-producing cells is essential for the development of cell-based therapies to reduce the progression of fibrotic diseases. Since HSP47 has a single substrate, which is collagen, the HSP47 cellular expression provides a novel universal biomarker to identify phenotypically altered collagen-producing cells during wound healing and fibrosis. In this brief article, we explained why HSP47 could be used as a universal marker for identifying phenotypically altered collagen-producing cells.

Dietary and genetic evidence for phosphate toxicity accelerating mammalian aging

Identifying factors that accelerate the aging process can provide important therapeutic targets for slowing down this process. Misregulation of phosphate homeostasis has been noted in various skeletal, cardiac, and renal diseases, but the exact role of phosphate toxicity in mammalian aging is not clearly defined. Phosphate is widely distributed in the body and is involved in cell signaling, energy metabolism, nucleic acid synthesis, and the maintenance of acid-base balance by urinary buffering. In this study, we used an in vivo genetic approach to determine the role of phosphate toxicity in mammalian aging. Klotho-knockout mice (klotho(-/-)) have a short life span and show numerous physical, biochemical, and morphological features consistent with premature aging, including kyphosis, uncoordinated movement, hypogonadism, infertility, severe skeletal muscle wasting, emphysema, and osteopenia, as well as generalized atrophy of the skin, intestine, thymus, and spleen. Molecular and biochemical analyses suggest that increased renal activity of sodium-phosphate cotransporters (NaPi2a) leads to severe hyperphosphatemia in klotho(-/-) mice. Genetically reducing serum phosphate levels in klotho(-/-) mice by generating a NaPi2a and klotho double-knockout (NaPi2a(-/-)/klotho(-/-)) strain resulted in amelioration of premature aging-like features. The NaPi2a(-/-)/klotho(-/-) double-knockout mice regained reproductive ability, recovered their body weight, reduced their organ atrophy, and suppressed ectopic calcifications, with the resulting effect being prolonged survival. More important, when hyperphosphatemia was induced in NaPi2a(-/-)/klotho(-/-) mice by feeding with a high-phosphate diet, premature aging-like features reappeared, clearly suggesting that phosphate toxicity is the main cause of premature aging in klotho(-/-) mice. The results of our dietary and genetic manipulation studies provide in vivo evidence for phosphate toxicity accelerating the aging process and suggest a novel role for phosphate in mammalian aging.

In vivo genetic evidence for suppressing vascular and soft-tissue calcification through the reduction of serum phosphate levels, even in the presence of high serum calcium and 1,25-dihydroxyvitamin d levels

BACKGROUND

Klotho-knockout mice (klotho(-/-)) have increased renal expression of sodium/phosphate cotransporters (NaPi2a), associated with severe hyperphosphatemia. Such serum biochemical changes in klotho(-/-) mice lead to extensive soft-tissue anomalies and vascular calcification. To determine the significance of increased renal expression of the NaPi2a protein and concomitant hyperphosphatemia and vascular calcification in klotho(-/-) mice, we generated klotho and NaPi2a double-knockout (klotho(-/-)/NaPi2a(-/-)) mice.

METHODS AND RESULTS

Genetic inactivation of NaPi2a activity from klotho(-/-) mice reversed the severe hyperphosphatemia to mild hypophosphatemia or normophosphatemia. Importantly, despite significantly higher serum calcium and 1,25-dihydroxyvitamin D levels in klotho(-/-)/NaPi2a(-/-) mice, the vascular and soft-tissue calcifications were reduced. Extensive soft-tissue anomalies and cardiovascular calcification were consistently noted in klotho(-/-) mice by 6 weeks of age; however, these vascular and soft-tissue abnormalities were absent even in 12-week-old double-knockout mice. Klotho(-/-)/NaPi2a(-/-) mice also regained body weight and did not develop the generalized tissue atrophy often noted in klotho(-/-) single-knockout mice.

CONCLUSIONS

Our in vivo genetic manipulation studies have provided compelling evidence for a pathological role of increased NaPi2a activities in regulating abnormal mineral ion metabolism and soft-tissue anomalies in klotho(-/-) mice. Notably, our results suggest that serum phosphate levels are the important in vivo determinant of calcification and that lowering serum phosphate levels can reduce or eliminate soft-tissue and vascular calcification, even in presence of extremely high serum calcium and 1,25-dihydroxyvitamin D levels. These in vivo observations have significant clinical importance and therapeutic implications for patients with chronic kidney disease with cardiovascular calcification.

Inactivation of klotho function induces hyperphosphatemia even in presence of high serum fibroblast growth factor 23 levels in a genetically engineered hypophosphatemic (Hyp) mouse model

Hyp mice possess a mutation that inactivates the phosphate-regulating gene, which is homologous to the endopeptidases of the X-chromosome (PHEX). The mutation is associated with severe hypophosphatemia due to excessive urinary phosphate wasting. Such urinary phosphate wasting in Hyp mice is associated with an increased serum accumulation of fibroblast growth factor (FGF) 23. We wanted to determine the biological significance of increased serum FGF23 levels and concomitant hypophosphatemia in Hyp mice and to evaluate whether FGF23 activity could be modified by manipulating klotho (a cofactor of FGF23 signaling). We generated Hyp and klotho double-mutant mice (Hyp/klotho(-/-)). Severe hypophosphatemia of Hyp mice was reversed to hyperphosphatemia in Hyp/klotho(-/-) double mutants, despite the fact that the double mutants showed significantly increased serum levels of FGF23. Hyperphosphatemia in Hyp/klotho(-/-) mice was associated with increased renal expression of sodium/phosphate cotransporter 2a (NaPi2a) protein. Exogenous injection of bioactive parathyroid hormone 1-34 down-regulated renal expression of NaPi2a and consequently reduced serum levels of phosphate in Hyp/klotho(-/-) mice. Moreover, in contrast to the Hyp mice, the Hyp/klotho(-/-) mice showed significantly higher serum levels of 1,25-dihydroxyvitamin D and developed extensive calcification in soft tissues and vascular walls. Furthermore, compared with the Hyp mice, Hyp/klotho(-/-) mice were smaller in size, showed features of generalized tissue atrophy, and generally died by 15-20 wk of age. Our in vivo studies provide genetic evidence for a pathological role of increased FGF23 activities in regulating abnormal phosphate homeostasis in Hyp mice. Moreover, these results suggest that even when serum levels of FGF23 are significantly high, in the absence of klotho, FGF23 is unable to regulate systemic phosphate homeostasis. Our in vivo observations have significant clinical implications in diseases associated with increased FGF23 activity and suggest that the functions of FGF23 can be therapeutically modulated by manipulating the effects of klotho.

Intraperitoneally applied gentamicin increases collagen content and mechanical stability of colon anastomosis in rats

BACKGROUND

Anastomotic leakage remains a serious complication in colorectal surgery, and is being caused by a multitude of factors. Recent reports reveal changes of the extracellular matrix as risk factors as well as gentamicin as a potential agent to influence wound healing. This experimental study was initiated to investigate the influence of intraperitoneally applied gentamicin on colonic anastomotic wound healing and in particular on mechanical stability, overall collagen content and collagen type I/III ratio.

MATERIALS AND METHODS

Sixty Sprague Dawley rats were randomized to one of two groups. In each animal, a standard transverse colonic end-to-end anastomosis was performed. Immediately postoperative, either 5 ml gentamicin (1 ml/kg bodyweight) or NaCl 0.9% was applied intraperitoneally. On postoperative days 3, 5, and 14, ten of the animals in each group were sacrificed. Measurements of the anastomosis bursting pressure were performed on postoperative days 3 and 5. At each explantation time, the collagen per protein ratio, the collagen types I/III ratio, and both the expression of MMP-2, -9, and Ki67 were analyzed.

RESULTS

None of the animals died. None of the rats exhibited clinical evidence of anastomotic leakage. The bursting strength in the gentamicin group was significantly elevated on postoperative day 5. Both the overall collagen content and the collagen type I/III ratio in the gentamicin group were significantly increased 3, 5, and 14 days postoperatively compared to the control group. The expression of MMP-9 was significantly elevated in the gentamicin group both 3 and 5 days postoperatively. In contrast, there were no significant differences in the expression of MMP-9 14 days postoperatively. All investigated samples demonstrated positive staining for MMP-2 and Ki67 without statistically significant differences at any term, respectively.

CONCLUSIONS

The present data confirm that intraperitoneally applied gentamicin is able to enhance healing and stability of colonic anastomosis due to an increase of both the overall collagen content and collagen type I/III ratio.

Reversal of mineral ion homeostasis and soft-tissue calcification of klotho knockout mice by deletion of vitamin D 1alpha-hydroxylase

Changes in the expression of klotho, a beta-glucuronidase, contribute to the development of features that resemble those of premature aging, as well as chronic renal failure. Klotho knockout mice have increased expression of the sodium/phosphate cotransporter (NaPi2a) and 1alpha-hydroxylase in their kidneys, along with increased serum levels of phosphate and 1,25-dihydroxyvitamin D. These changes are associated with widespread soft-tissue calcifications, generalized tissue atrophy, and a shorter lifespan in the knockout mice. To determine the role of the increased vitamin D activities in klotho knockout animals, we generated klotho and 1alpha-hydroxylase double-knockout mice. These double mutants regained body weight and developed hypophosphatemia with a complete elimination of the soft-tissue and vascular calcifications that were routinely found in klotho knockout mice. The markedly increased serum fibroblast growth factor 23 and the abnormally low serum parathyroid hormone levels, typical of klotho knockout mice, were significantly reversed in the double-knockout animals. These in vivo studies suggest that vitamin D has a pathologic role in regulating abnormal mineral ion metabolism and soft-tissue anomalies of klotho-deficient mice.

In vivo genetic evidence for klotho-dependent, fibroblast growth factor 23 (Fgf23) -mediated regulation of systemic phosphate homeostasis

A major breakthrough in systemic phosphate homeostasis regulation was achieved by the demonstration of strikingly similar physical, morphological, and biochemical phenotypes of fibroblast growth factor 23 (Fgf23) and klotho ablated mice, which led to identification of klotho as an Fgf23 signaling cofactor. Here, we generated Fgf23 and klotho double-knockout (Fgf23(-/-)/klotho(-/-)) mice to test the hypothesis whether Fgf23 has a klotho-independent function. Fgf23(-/-)/klotho(-/-) mice are viable and have high serum phosphate levels, similar to Fgf23(-/-) and klotho(-/-) single-knockout mice. In addition, the Fgf23(-/-)/klotho(-/-) mice have increased renal expression of the sodium/phosphate cotransporter NaP(i)2a and of 1- alpha-hydroxylase concomitant with increased serum levels of 1,25-dihydroxyvitamin-D, as also observed in the Fgf23(-/-) and klotho(-/-) mice. Moreover, Fgf23(-/-)/klotho(-/-) mice show soft tissue and vascular calcification, severe muscle wasting, hypogonadism, pulmonary emphysema, distention of intestinal wall, and skin atrophy, all of which are also seen in Fgf23(-/-) and klotho(-/-) mice. Notably, injection of bioactive FGF23 protein into Fgf23(-/-)/klotho(-/-) and klotho(-/-) mice does not lower serum phosphate, whereas in wild-type and Fgf23(-/-) mice, it reduces serum phosphate. Together, these results provide compelling evidence that Fgf23 does not have a klotho-independent role in the regulation of systemic phosphate and vitamin D homeostasis.

Low-dose local kidney irradiation inhibits progression of experimental crescentic nephritis by promoting apoptosis

BACKGROUND

Crescentic glomerulonephritis is a rapidly progressive form of nephritis and is usually resistant to therapeutic intervention. Apoptosis plays a role in the resolution of glomerulonephritis. We investigated the effects of local kidney irradiation on the progression of experimental crescentic glomerulonephritis.

METHODS

The following three experimental rat groups were generated: (1) Group I, sham-operated control (n = 12); (2) Group II, rats injected intravenously with rabbit anti-rat GBM antibody (nephrotoxic serum, NTS) (n = 23), and (3) Group III, a single low-dose irradiation of 0.5 Gy X-ray to both kidneys at days 6, 13, 20, and 27 after NTS injection (n = 55). Renal function and blood leukocyte count were examined in different groups of rats at various time points. Kidneys obtained at various time points were analyzed to determine the effects of radiation in experimental nephritis.

RESULTS

Radiation of the kidneys reduced the levels of blood urea nitrogen and serum creatinine compared with Group II nephritic rats of similar age (p < 0.05 or 0.001). No apparent changes in blood leukocyte counts were noted in various experimental groups. Glomerular hypercellularity, crescents, global sclerosis and tubulointerstitial damage developed gradually in Group II rats, but were decreased (p < 0.05 or 0.001) after radiation treatment. The extent of tubulointerstitial damage was also reduced, and radiation-associated histological improvements were accompanied by reduced infiltration of macrophages in the glomeruli and interstitium. The numbers of PCNA- and ED1-positive cells were reduced in the kidneys at 1 day post-irradiation, of rats irradiated at 6 and 13 days after NTS injection, compared with Group II at similar time intervals (p < 0.05). A larger numbers of TUNEL-positive cells were noted at 1 day post-irradiation in rats irradiated at 6 and 13 days after NTS injection, compared with Group II at similar time intervals (p < 0.05). Immunostaining for macrophages ED1 and TUNEL staining of serial sections of irradiated nephritic kidneys showed few ED1-positive macrophages stained for TUNEL. Overexpression of active caspases 3 and 7 was noted in irradiated kidneys, compared with the corresponding Group II rats at similar time intervals. Western blot analysis showed marked increase in active caspase 3 and active caspase 7 expression in irradiated kidneys compared with NTS injection only. A marked increase in the expression of p53 protein, which is closely related to radiation-induced apoptosis, was also observed in irradiated kidneys compared with NTS injection only.

CONCLUSION

Our study showed that renal radiation can alter acute glomerular inflammation by inducing apoptosis of intrinsic and infiltrating cells in the kidney in a rat model of crescentic glomerulonephritis. Low-dose kidney irradiation can inhibit the progression of experimental nephritis through inducing apoptosis.

Does renal ageing affect survival?

The effects of ageing on progressive deterioration of renal function, both in human and experimental animals, are described elsewhere, but the effect of renal damage on overall survival and longevity is not yet clearly established. The wild-type animals of various genetic backgrounds, fed with regular diet, overtime develop severe age-associated nephropathy, that include but not limited to inflammatory cell infiltration, glomerulosclerosis, and tubulointerstitial fibrosis. Such renal damage significantly reduces their survival. Reducing renal damage, either by caloric restriction or by suppressing growth hormone (GH)/insulin-like growth factor-1 (IGF-1) activity could significantly enhance the longevity of these animals. Available survival studies using experimental animals clearly suggest that kidney pathology is one of the important non-neoplastic lesions that could affect overall survival, and that restoration of renal function by preventing kidney damage could significantly extend longevity. Careful long-term studies are needed to determine the human relevance of these experimental studies.

Suppression of renal tubulointerstitial fibrosis by small interfering RNA targeting heat shock protein 47

BACKGROUND/AIM

Unilateral ureteral obstruction (UUO) is a well-established model for tubulointerstitial fibrosis. During the progression of tubulointerstitial fibrosis, upregulation of collagen synthesis and subsequent accumulation of collagen were observed in the tubulointerstitial area. Heat shock protein 47 (HSP47) is a collagen-specific molecular chaperone and plays an essential role in regulating collagen synthesis. We designed small interfering RNA (siRNA) sequences for HSP47 mRNA to examine whether HSP47 is involved in the progression of renal tubulointerstitial fibrosis in a mouse UUO model.

METHODS

The HSP47 siRNA was injected once via the ureter at the time of UUO preparation. We also applied a new gene delivery system for siRNA using cationized gelatin microspheres. The kidneys were harvested 7 and 14 days after UUO. The HSP47 and type I, III, and IV collagen expression levels were analyzed by immunohistochemistry and Western blotting.

RESULTS

Seven days after UUO, the expression levels of HSP47 and type I, III, and IV collagens were markedly upregulated in obstructed kidneys or green fluorescent protein siRNA treated obstructed kidneys. HSP47 siRNA injection significantly reduced the protein expression levels and significantly diminished the accompanying interstitial fibrosis. Moreover, cationized gelatin microspheres as a delivery system enhanced and lengthened the antifibrotic effect of HSP47 siRNA.

CONCLUSIONS

Our results indicate that HSP47 is a candidate target for the prevention of tubulointerstitial fibrosis and that selective blockade of the HSP47 expression by using siRNA could be a potentially useful therapeutic approach for patients with renal disease.

Antisense oligonucleotide inhibition of heat shock protein (HSP) 47 improves bleomycin-induced pulmonary fibrosis in rats

Background

The most common pathologic form of pulmonary fibrosis arises from excessive deposition of extracellular matrix proteins such as collagen. The 47 kDa heat shock protein 47 (HSP47) is a collagen-specific molecular chaperone that has been shown to play a major role during the processing and/or secretion of procollagen.

Objectives

To determine whether inhibition of HSP47 could have beneficial effects in mitigating bleomycin-induced pulmonary fibrosis in rats.

Methods

All experiments were performed with 250–300 g male Wistar rats. Animals were randomly divided into five experimental groups that were administered: 1) saline alone, 2) bleomycin alone, 3) antisense HSP47 oligonucleotides alone, 4) bleomycin + antisense HSP47 oligonucleotides, and 5) bleomycin + sense control oligonucleotides. We investigated lung histopathology and performed immunoblot and immunohistochemistry analyses.

Results

In rats treated with HSP47 antisense oligonucleotides, pulmonary fibrosis was significantly reduced. In addition, treatment with HSP47 antisense oligonucleotides significantly improved bleomycin-induced morphological changes. Treatment with HSP47 antisense oligonucleotides alone did not produce any significant changes to lung morphology. Immunoblot analyses of lung homogenates confirmed the inhibition of HSP47 protein by antisense oligonucleotides. The bleo + sense group, however, did not exhibit any improvement in lung pathology compared to bleomycin alone groups, and also had no effect on HSP47 expression.

Conclusion

These findings suggest that HSP47 antisense oligonucleotide inhibition of HSP47 improves bleomycin-induced pulmonary fibrosis pathology in rats.

An antisense oligonucleotide to HSP47 inhibits paraquat-induced pulmonary fibrosis in rats

The most common cause of death from poisoning by the widely used, but highly toxic herbicide paraquat is respiratory failure from pulmonary fibrosis, which develops through pathological overproduction of extracellular matrix proteins such as the collagens. Heat shock protein (HSP47) is a collagen-specific molecular chaperone that assists in the posttranslational modifications of procollagens during collagen biosynthesis. We investigated whether treatment with an HSP47-antisense oligonucleotide would inhibit paraquat-induced pulmonary fibrosis in Wistar rats. Rats randomized into three groups (control, paraquat, and paraquat+antisense). Paraquat (20 mg/kg/day) (n=16) or a saline control (n=10) was administered to groups of Wistar rats. Intratracheal administration of the antisense oligonucleotide (100 nmol/kg in saline) was performed after the initial paraquat treatment (n=16). Treatment with paraquat alone induced pulmonary fibrosis in the entire group, while treatment with the antisense oligonucleotide alone did not produce any substantial change in lung histology. Administration of antisense oligonucleotides produced a substantial reduction in paraquat-induced pulmonary fibrosis. An immunoblot analysis confirmed that the HSP47-antisense oligonucleotide inhibited HSP47 production. These findings indicate that the HSP47-antisense oligonucleotide inhibited paraquat-induced pulmonary fibrosis and pneumopathy in rats.

Introduction of antisense oligonucleotides to heat shock protein 47 prevents pulmonary fibrosis in lipopolysaccharide-induced pneumopathy of the rat

Acute respiratory distress syndrome (ARDS) confers high morbidity, and in part due to pulmonary fibrosis. The 47-kDa heat shock protein 47 (HSP 47) is a collagen-specific molecular chaperone that has been shown to play a major role in the processing and secretion of procollagen. We examined the effect of antisense oligonucleotides against HSP 47 in Wistar rats with lipopolysaccharide (LPS)-induced pulmonary fibrosis. These rats expressed heat shock protein (HSP) 47 and collagen in response to LPS. The distribution of HSP 47 was similar to that of collagen, and all control rats displayed pulmonary fibrosis after intratracheal administration of 20 mg/kg LPS alone. Antisense oligonucleotides (100 nmol/kg dissolved in saline) were administered with the LPS among experimental subjects. Subsequent immunoblot analysis confirmed the inhibition of HSP 47 by the administration of antisense oligonucleotides. The oligonucleotides significantly improved pulmonary fibrosis among those rats administered LPS, but the oligonucletides themselves did not produce any significant changes in the behavior or histology of the lungs among control rats. These findings suggest that HSP 47 antisense oligonucleotides improve lung fibrosis among rats with LPS-induced pneumopathy.

The collagen-specific molecular chaperone HSP47: is there a role in fibrosis?

Heat shock protein 47 (HSP47) is a collagen-specific molecular chaperone that is required for molecular maturation of various types of collagens. Recent studies have shown a close association between increased expression of HSP47 and excessive accumulation of collagens in scar tissues of various human and experimental fibrotic diseases. It is presumed that the increased levels of HSP47 in fibrotic diseases assist in excessive assembly and intracellular processing of procollagen molecules and, thereby, contribute to the formation of fibrotic lesions. Studies have also shown that suppression of HSP47 expression can reduce accumulation of collagens to delay the progression of fibrotic diseases in experimental animal models. Because HSP47 is a specific chaperone for collagen synthesis, it provides a selective target to manipulate collagen production, a phenomenon that might have enormous clinical impact in controlling a wide range of fibrotic diseases. Here, we outline the fibrogenic role of HSP47 and discuss the potential usefulness of HSP47 as an anti-fibrotic therapeutic target.

Oxidative stress during peritoneal dialysis: implications in functional and structural changes in the membrane

Progressive peritoneal fibrosis, membrane hyperpermeability, and ultrafiltration failure have been observed in patients on long-term peritoneal dialysis (PD). The present study tested the hypothesis that reactive oxygen species (ROS) generated by conventional PD solution (PDS) mediate functional and structural alterations of peritoneal membrane in vivo. Sprague-Dawley rats were randomized to control, PDS, PDS with an antioxidant, and PDS with an angiotensin II (Ang II) receptor blocker. Commercial PDS containing 3.86% glucose (20-30 ml) with or without N-acetylcystein (NAC) 10 mM or losartan 5 mg/kg was administered intraperitoneally twice a day for 12 weeks. Control rats received sham injection. Rats treated with PDS had significantly lower drain volume and D(4)/D(0) glucose, but higher D(4)/P(4) creatinine and increased membrane thickness and endothelial NOS (eNOS) expression compared to control rats. Omental transforming growth factor (TGF)-beta1, vascular endothelial growth factor (VEGF), collagen I, and heat-shock protein (hsp) 47 expression and lipid peroxide levels and dialysate VEGF and Ang II concentrations were significantly increased in rats treated with PDS compared to control. All of these changes were prevented by both NAC and losartan. In conclusion, the present study demonstrates that ROS generated by conventional PDS are, in large part, responsible for peritoneal fibrosis and membrane hyperpermeability. We suggest that antioxidants or Ang II receptor blockers may allow better preservation of the structural and functional integrity of the peritoneal membrane during long-term PD.

Premature aging-like phenotype in fibroblast growth factor 23 null mice is a vitamin D-mediated process

Fibroblast growth factor 23 null mice (Fgf-23-/-) have a short lifespan and show numerous biochemical and morphological features consistent with premature aging-like phenotypes, including kyphosis, severe muscle wasting, hypogonadism, osteopenia, emphysema, uncoordinated movement, T cell dysregulation, and atrophy of the intestinal villi, skin, thymus, and spleen. Furthermore, increased vitamin D activities in homozygous mutants are associated with severe atherosclerosis and widespread soft tissue calcifications; ablation of vitamin D activity from Fgf-23-/- mice, by genetically deleting the 1alpha(OH)ase gene, eliminates atherosclerosis and ectopic calcifications and significantly rescues premature aging-like features of Fgf-23-/- mice, resulting in prolonged survival of Fgf-23-/-/1alpha(OH)ase-/- double mutants. Our results indicate a novel role of Fgf-23 in developing premature aging-like features through regulating vitamin D homeostasis. Finally, our data support a new model of interactions among Fgf-23, vitamin D, and klotho, a gene described as being associated with premature aging process.

Interstitial expression of heat-shock protein 47 correlates with capillary deposition of complement split product C4d in chronic allograft nephropathy

BACKGROUND

Chronic allograft nephropathy (CAN), associated with late-allograft dysfunction is caused by alloantigen-dependent and -independent mechanisms, and eventually leads to interstitial fibrosis (ci). Activation of complement cascade is considered to be a poor prognostic marker of graft survival. This study was designed to examine the relationship between the expression of C4d and heat-shock protein 47 (HSP47, a collagen-specific chaperone) in the development of interstitial fibroproliferative lesions in CAN.

METHODS

Sixty-three renal allograft biopsy specimens, obtained from 48 patients, were examined for the expression of C4d, HSP47, CD68 and alpha-smooth muscle actin (alpha-SMA) by immunohistochemistry. Double-staining was performed to determine the colocalization of C4d and HSP47. The relationship of between the expression of C4d, HSP47, CD68 and alpha-SMA and the clinical and histopathological parameters were statistically analysed.

RESULTS

No expression of C4d was noted in the tubulointerstitium including peritubular capillary (PTC) of the control kidney. C4d was expressed in PTC in one-third of allograft renal tissues with morphological evidences of CAN. The interstitial cells around the fibrotic areas of the PTC of CAN were positive for the expression of HSP47. The deposition of C4d in PTC correlated with interstitial expression of HSP47 around the PTC. Most HSP47 expressing cells were phenotypically altered myofibroblasts, as determined by the dual staining of alpha-SMA.

CONCLUSIONS

The increased expression of HSP47 positively correlated with the expression of C4d in PTC, and might contribute to the progression of interstitial ci in CAN.

Identification of small molecule chemical inhibitors of the collagen-specific chaperone Hsp47

Hsp47 is a collagen-specific molecular chaperone whose activity has been implicated in the pathogenesis of fibrotic diseases. Here, we describe the development of an assay for screening libraries of chemical compounds for inhibitors of Hsp47. A preliminary screen of 2080 compounds identified four that demonstrated inhibitory activity against Hsp47 in vitro, with IC(50) values ranging from 3 to 27 muM. Compounds identified through this method may provide the basis for development of novel antifibrotic therapeutics.

Antisense oligonucleotides against collagen-binding stress protein HSP47 suppress peritoneal fibrosis in rats

BACKGROUND

Peritoneal fibrosis is a serious complication in patients on continuous ambulatory peritoneal dialysis (CAPD), but the molecular mechanism of this process remains unclear. Heat shock protein 47 (HSP47), a collagen-specific molecular chaperone, is essential for biosynthesis and secretion of collagen molecules, and is expressed in the tissue of human peritoneal fibrosis. In the present study, we examined the effect of HSP47 antisense oligonucleotides (ODNs) on the development of experimental peritoneal fibrosis induced by daily intraperitoneal injections of chlorhexidine gluconate (CG).

METHODS

HSP47 antisense or sense ODNs were injected simultaneously with CG from day 14, after injections of CG alone. Peritoneal tissue was dissected out 28 days after CG injection. The expression patterns of HSP47, type I and type III collagen, alpha-smooth muscle actin (alpha-SMA), as a marker of myofibroblasts, ED-1 (as a marker of macrophages), and factor VIII were examined by immunohistochemistry.

RESULTS

In rats treated with CG alone, the submesothelial collagenous compact zone was thickened, where the expression levels of HSP47, type I and type III collagen and alpha-SMA were increased. Marked macrophage infiltration was also noted and the number of vessels positively stained for factor VIII increased in the CG-treated group. Treatment with antisense ODNs, but not sense ODNs, abrogated CG-induced changes in the expression of HSP47, type I and III collagen, alpha-SMA, and the number of infiltrating macrophages and vessels.

CONCLUSION

Our results indicate the involvement of HSP47 in the progression of peritoneal fibrosis and that inhibition of HSP47 expression might merit further clinical investigation for the treatment of peritoneal fibrosis in CAPD patients.

Antisense oligonucleotide against collagen-specific molecular chaperone 47-kDa heat shock protein suppresses scar formation in rat wounds

The 47-kDa heat shock protein (HSP47) is a molecular chaperone specifically targeting the processing and quality control of collagen molecules. This study was performed to investigate whether antisense therapy preventing HSP47 expression might affect the scar formation occurring during wound healing of skin. In wound healing of neonatal rat skin, the number of HSP47-positive cells and the amount of HSP47 protein consistently increased up to 7 days after surgical wounding. The increase in HSP47-positive cell number and protein content was efficiently suppressed by daily injections of HSP47-antisense deoxynucleotide (30 nmol) for 7 days. This treatment also suppressed the accumulation of collagen type I in the wound. Moreover, the disorder of collagenous fibers was relieved in the healed portion of the wounds subjected to the antisense treatment. Taken together, the authors propose that HSP47 is an important determinant in scar formation and that the antisense treatment against HSP47 gene may have a therapeutic potential to suppress the scar formation of skin.

Induction of heat shock protein 47 synthesis by TGF-beta and IL-1 beta via enhancement of the heat shock element binding activity of heat shock transcription factor 1

With most immunological reactions, tissue fibrosis, collagen overproduction caused by immune cytokines, is inevitably associated. Among the various immune cytokines, heat shock protein 47 (HSP47) is a procollagen-specific molecular chaperon and is essential for secretion of procollagen from cells. Induction of HSP47 by TGF-beta has been previously reported in rat skeletal myoblasts and mouse osteoblasts, but not in human diploid fibroblasts. As for IL-1beta, its effect on HSP47 has not been elucidated. In the present study, using human embryonic lung fibroblast cells, we first disclosed that both TGF-beta and IL-1beta induced HSP47 synthesis. We then revealed that the binding of the heat shock element (HSE) by heat shock transcription factor 1 (HSF1) was enhanced by both cytokines. We further demonstrated that trimer formation of HSF1, which is essential for its binding to HSE, was induced by these cytokines. The enhancement of HSP47 synthesis and their trimer formation of HSF1 were augmented by using a combination of both cytokines. Collectively, TGF- beta and IL-1beta were found to induce trimer formation of HSF1 which in turn bound to HSE of HSP47, resulting in the enhancement of HSP47 expression. Thus, HSP47 could well be a good candidate for molecular targeting in controlling tissue fibrosis, given that both principal fibrinogenetic cytokines (TGF-beta, IL-1beta) are commonly involved in its induction through HSF1 trimerization.

Collagen-binding heat shock protein HSP47 expression during healing of fetal skin wounds

Wounds in fetal animals are known to heal without scar formation, but the mechanism involved remains unclear. Scar tissue is characterized by disorganized collagen bundles. The 47-kDa heat shock protein (HSP47) is a molecular chaperone that specifically targets collagen processing. However, the role of HSP47 in scar formation is poorly understood. We studied the relation of HSP47 expression in skin to scar formation during fetal wound healing. Immunohistochemical analysis demonstrated HSP47-positive cells in the epidermal cell layer of fetal and neonatal rat skin and the absence of such cells in subcutaneous tissue. After induction of a wound on the back of fetal and neonatal rats, the message of collagen type I was increased only in neonatal skin but not in fetal skin. HSP47-positive cells consistently increased for 7 days after wound induction in neonatal rats. In contrast, HSP47-positive cells and HSP47 protein were unchanged in fetal rats. We conclude that the scarless healing of fetal skin wounds is related to lack of change in HSP47 expression. HSP47 may thus be an important determinant of scar formation during wound healing.

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.

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.

Heat shock protein (HSP) 47 and collagen are upregulated during neointimal formation in the balloon-injured rat carotid artery

Heat shock protein (HSP) 47, a collagen-specific molecular chaperone, is thought to be essential for the proper processing and secretion of procollagen molecules. We investigated the time course and localization of HSP47 and collagen expression after balloon catheter angioplasty in the rat carotid artery, based on the premise that accumulation of extracellular matrix components is a main feature of intimal hyperplasia in humans and in laboratory animals. Low levels of HSP47 expression were evident in uninjured carotid arteries. Northern blot analysis revealed that HSP47 mRNA expression was markedly stimulated 1--3 days after the induced injury and a high level was maintained for 7 days, followed by a gradual decline for up to 21 days after the injury. These changes in HSP47 expression paralleled changes in alpha 1(I) collagen expression. Immunohistochemical staining revealed colocalization of HSP47 and collagen in smooth muscle cells (SMCs) of the media and intima. In situ hybridization analysis showed that activated SMCs, which proliferated and migrated into the intima, expressed high levels of HSP47. In cultured human aortic SMCs, similar upregulation of HSP47 and alpha1(I) collagen by TGF-beta was noted. These results show that SMCs activated after balloon injury express high levels of HSP47 and collagen during cell proliferation and migration, hence an overproduction of collagen and development of intimal thickening. Thus, HSP47 plays a role in the formation and progression of neointima after angioplasty.

Renal expression of the Ets-1 proto-oncogene during progression of rat crescentic glomerulonephritis

The ets-1 proto-oncogene is a member of the transcriptional factor family and was identified by homology to the v-ets oncogene. It was recently demonstrated that Ets-1 protein interacts with the promoter region of the genes coding for proteinases, including matrix metalloproteinase-1 (MMP-1), MMP-3, and urokinase-type plasminogen activator, suggesting that it may play an important role in the regulation of MMP expression. The role of the ets-1 proto-oncogene in advanced glomerular diseases, where extracellular matrix accumulation is observed, remains undefined. In this study, the expression of ets-1 mRNA and protein during the progression of rat crescentic glomerulonephritis was examined using immunohistochemical analysis, reverse transcription-PCR, and in situ hybridization. Passive accelerated anti-glomerular basement membrane-induced nephritis was induced in rats by intravenous injection of nephrotoxic serum. Rats were euthanized on day 7, 14, 21, 28, or 42. Immunohistochemical analysis demonstrated significant upregulation of Ets-1 protein expression in glomeruli and the interstitium in anti-glomerular basement membrane-induced nephritis. The numbers of Ets-1-positive cells were increased 8.8-fold on day 21 in glomeruli (1.2+/-0.1 cells/glomerular cross-section, P<0.001) and sixfold on day 28 in the interstitium (21+/-1.3 cells/mm(2), P<0.001), compared with control samples. Ets-1 protein was predominantly localized in glomerular epithelial cells, endothelial cells, and interstitial cells. A small number of vascular endothelial cells, macrophages, and T cells also expressed Ets-1 protein. MMP-3 deposition was upregulated and positive cells in the interstitium often coexpressed Ets-1, whereas only a few glomerular cells were positive for both MMP-3 and Ets-1 protein. The expression of ets-1 mRNA was also markedly increased in diseased kidneys. The distribution of ets-1 mRNA was similar to that of the protein. These results indicate that overexpression of the ets-1 proto-oncogene by phenotypically altered renal cells might be associated with the pathogenesis of rat crescentic glomerulonephritis.

Increase in expression of Hsp47 and collagen in hereditary gingival fibromatosis is modulated by stress and terminal procollagen N-propeptides

HGF is a rare oral condition characterized by a slow, progressive enlargement of the gingiva, involving both the maxilla and mandible. HGF provides a model for the study of regulatory features of conditions characterized by connective tissue hyperplasia. In this study, the culture characteristics of gingival fibroblasts derived from patients of the same family with HGF (n = 4) were similar with regard to cell cycle analysis. Flow cytometric DNA content analysis revealed uniform DNA diploidy for fibroblasts cultured from NG and HGF. NG cells showed a low S-phase fraction (19.8%) and G2/M fraction (5.8%) and a relatively high G1 phase fraction (74%). In contrast, HGF cells from all members of the tested kindred, exhibited diploid cells with a higher S-phase (40.9%) and G2/M (10.1%) fraction and a relatively low G1 phase fraction (40.9%). Furthermore, we demonstrated that the expression and production of Hsp47 parallels the increased levels of collagen secretion observed in HGF. In addition, we show that Hsp47 and collagen are coordinately regulated following stress via a feedback mechanism mediated by N-terminal procollagen propeptides. Utilizing confocal microscopy and antibodies directed against GST-fusion proteins encompassing the pro alpha1(I) N-propeptide globular domain (NP1) (residues 23-108), it was apparent that this regulatory mechanism does not involve significant interaction with Hsp47's chaperoning of procollagen.

Expression of heat shock proteins 47 and 70 in the peritoneum of patients on continuous ambulatory peritoneal dialysis

BACKGROUND

Peritoneal sclerosis, characterized by collagen accumulation, is a serious complication in continuous ambulatory peritoneal dialysis (CAPD) therapy. Heat shock protein 47 (HSP47) is a collagen-specific molecular chaperon and is closely associated with collagen synthesis.

METHODS

We determined the expression of HSP47 and HSP70 (nonspecific for collagen synthesis) by immunohistochemistry in peritoneal tissues of patients on CAPD. The tissue for collagen III, alpha-smooth muscle actin (alpha-SMA), and CD68 (a marker for macrophages) were also stained. Thirty-two peritoneal samples were divided into three groups (group A1, 11 patients who had no ultrafiltration loss; group A2, 9 patients who had ultrafiltration loss; and group B, 12 specimens who had end-stage renal disease prior to induction of CAPD.

RESULTS

In group B, staining for HSP47, HSP70, and collagen III in peritoneal tissues was faint, and only a few cells were positive for alpha-SMA and CD68. In contrast, HSP47, HSP70, and collagen III were expressed in areas of thickened connective tissues in fibrotic peritoneal specimens of CAPD patients. The expression level of HSP47, HSP70, collagen III, and alpha-SMA and the number of CD68-positive cells in group A2 were significantly higher than those in groups A1 and B. HSP47/HSP70-positive cells were mesothelial cells, adipocytes, and alpha-SMA-positive myofibroblasts. Furthermore, the expression level of HSP47 was significantly higher in peritoneal specimens from patients with refractory peritonitis than without it and was significantly higher in patients with more than 60 months of CAPD therapy than that in patients with less than 60 months of CAPD.

CONCLUSION

Our results indicate that CAPD therapy may induce HSPs in the peritoneal tissue, and that peritonitis in CAPD patients may be associated with the progression of peritoneal sclerosis at least through HSP47 expression and chronic macrophage infiltration. Our data also suggest that the progression of peritoneal sclerosis in such patients is associated with deterioration of peritoneal ultrafiltration function.

Greater than normal expression of the collagen-binding stress protein heat-shock protein-47 in the infarct zone in rats after experimentally-induced myocardial infarction

BACKGROUND

The heat-shock protein with relative molecular mass 47,000 (HSP47) can bind to procollagen molecules in the endoplasmic reticulum, and acts as a molecular chaperone during the processing and secretion of procollagen.

OBJECTIVE

To test our hypothesis that HSP47 is expressed in the myocardial infarct zone.

METHODS

We induced myocardial infarction in male Sprague-Dawley rats by ligation of left coronary artery. The expression of HSP47 was examined by Northern blotting, in-situ hybridization, Western blotting and immunohistochemistry. The time-dependent change in the distribution of HSP47 messenger RNA (mRNA) signal was compared with the changes in expression of alpha 1(I) and alpha 1(III) collagen mRNA by in-situ hybridization. The hypoxic induction of HSP47 in cultured cardiac fibroblasts was examined by Northern-blot analysis.

RESULTS

Northern blotting demonstrated that the expression of HSP47 mRNA had increased on day 2, reaching a maximum level around day 14 (induced 3.5-fold compared with the preligation hearts) and was maintained at a high level up to day 28. In-situ hybridization analysis revealed HSP47 mRNA signals in spindle-shaped mesenchymal cells located between surviving myocytes in the infarct's peripheral zone 24 h after the ligation, and in the entire infarct zone on day 14. The sequential changes in distribution of HSP47 mRNA signal were identical to those of the alpha 1(I) and alpha 1(III) collagen mRNA. Western blotting demonstrated that expression of HSP47 protein in the infarct zone had increased. Immunofluorescent staining revealed positivity for HSP47 in the infarct's peripheral zone on day 2 and in the entire infarct zone on day 14. Northern blotting revealed that the expression of HSP47 mRNA in cultured cardiac fibroblasts in hypoxic cultures was greater than that in normoxic cultures.

CONCLUSION

The present data demonstrated that an increase in expression of HSP47 is produced by spindle-shaped mesenchymal cells in the infarct zone. Expression of HSP47 mRNA was concurrent with the expression of collagen mRNA of types I and III. Hypoxia is one of the factors which induces expression of HSP47.

Substrate recognition of collagen-specific molecular chaperone HSP47. Structural requirements and binding regulation

Prior to secretion, procollagen molecules are correctly folded to triple helices in the endoplasmic reticulum (ER). HSP47 specifically associates with procollagen in the ER during its folding and/or modification processes and is thought to function as a collagen-specific molecular chaperone (Nagata, K. (1996) Trends Biochem. Sci. 21, 23-26). However, structural requirements for substrate recognition and regulation of the binding have not yet been elucidated. Here, we show that a typical collagen model sequence, (Pro-Pro-Gly)(n), possesses sufficient structural information required for recognition by HSP47. A structure-activity relationship study using synthetic analogs of (Pro-Pro-Gly)(n) has revealed the requirements in both chain length and primary structure for the interaction. The substrate recognition of HSP47 has also been shown to be similar but distinct from that of prolyl 4-hydroxylase, an ER resident enzyme. Further, it has shown that the interaction of HSP47 with the substrate peptides is abolished by prolyl 4-hydroxylation of the second Pro residues in Pro-Pro-Gly triplets and that the fully prolyl 4-hydroxylated peptide, (Pro-Hyp-Gly)(n), does not interact with HSP47. We thus have proposed a model in which HSP47 dissociates from procollagen during the process of prolyl 4-hydroxylation in the ER.

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.

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.