Advanced glycation end products in age-related macular degeneration

OBJECTIVE

To investigate the localization of N epsilon-(carboxymethyl)lysine (CML), a component and major immunologic epitope of advanced glycation end products, in aged eyes and choroidal neovascular membranes (CNVMs) surgically excised from eyes with age-related macular degeneration.

METHODS

Immunohistochemistry for CML was performed using 8 snap-frozen, surgically excised CNVMs. Twelve eyes from patients aged 69 to 82 years and 2 donor eyes, 1 each from a 23-week-old fetus and 21-year-old patient, without age-related macular degeneration or diabetic retinopathy were also examined. To determine if retinal pigment epithelial cells in CNVMs accumulate advanced glycation end products, cytokeratin and CML were stained in paired serial sections.

RESULTS

Soft, macular drusen and/or basal laminar and basal linear deposits were observed in 8 of 12 aged eyes. Each case showed CML accumulation, while overlying retinal pigment epithelial cells showed no accumulation in all 12 eyes. In CNVMs, however, retinal pigment epithelial cells showed CML accumulation in their cytoplasm.

CONCLUSION

The additional accumulation of advanced glycation end products in soft, macular drusen and/or retinal pigment epithelial cells may play a role in the pathogenesis of CNVM formation in age-related macular degeneration.

CLINICAL RELEVANCE

Recently, advanced glycation end products have been found to play a role both in aging changes and neovascularization. Localization of advanced glycation end products in the above-mentioned tissue may lead to a better understanding of the pathogenesis of age-related macular degeneration.

Immunohistochemical distribution and subcellular localization of three distinct specific molecular structures of advanced glycation end products in human tissues

Using three mouse anti-human monoclonal antibodies for advanced glycation end products (AGEs), 6D12, 1F6, and 2A2, we examined the immunohistochemical distribution and localization of AGEs in various organs and tissues obtained from nondiabetic autopsy or biopsy cases (men and women, 41 to 86 years of age). 6D12 recognizes Nepsilon-(carboxymethyl)lysine (CML), a nonfluorescent and non-cross-linked AGE structure, and 1F6 recognizes fluorolink, a fluorescent and cross-linked AGE structure. The epitope of 2A2 is unknown but is different from that of CML and fluorolink or other known AGE structures such as pyrraline, pentosidine, and crosslines. Immunohistochemistry with these monoclonal antibodies revealed the intra- and extracellular accumulation of AGEs in these organs and tissues. By double immunohistochemical staining with two of the three monoclonal antibodies in different combinations, positive reaction products for all three monoclonal antibodies were demonstrated in macrophages widely distributed in various organs and tissues; endothelial cells of endocardium, arteries, veins, and blood capillaries; mesenchymal cells; epithelial or parenchymal cells; blood cells; and extracellular matrix. This result indicates that these three different AGE-specific molecules are formed intracellularly and extracellularly. In some cell types, however, one or two of these specific molecules were not always found together, suggesting that the molecular structures of AGEs and their formation are heterogeneous. Immunoelectron microscopy demonstrated the localization of AGE-labeled immunogold particles in the nuclei, nuclear envelope, mitochondria, endoplasmic reticula, Golgi complexes, endocytic vesicles, lysosomal vacuoles or granules, secretory granules, cytosol, and cell membranes, as well as in the extracellular matrix. In addition, the double histochemical staining method for ceroid/lipofuscin and immunohistochemistry for AGEs demonstrated intralysosomal formation and accumulation of AGEs in ceroid/lipofuscin pigments. These results suggest that the extracellularly produced AGEs are taken up by receptors into the cells and accumulate in secondary lysosomes and that AGEs are formed intranuclearly and/or intracellularly, probably via different metabolic pathways.

Shedding of the soluble IL-6 receptor is triggered by Ca2+ mobilization, while basal release is predominantly the product of differential mRNA splicing in THP-1 cells

The soluble IL-6 receptor (sIL-6R) is generated through either proteolytic shedding of the cognate receptor (PC-sIL-6R), or released as the product of differential mRNA splicing (DS-sIL-6R). Using monocytic THP-1 cells, we demonstrate that both mechanisms are independently regulated, and that each process contributes to sIL-6R production. Shedding of the IL-6R was activated by the Ca2+ ionophore, ionomycin, and inhibited by the TNF-alpha protease inhibitor (TAPI). In contrast, basal sIL-6R release was unaffected by Ca2+ depletion and largely insensitive to TAPI. Moreover, although IL-6R shedding was inactivated by serum starvation, non-stimulated production remained intact. Basal sIL-6R production via differential mRNA splicing was shown through the inhibitory action of brefeldin A and an enzyme-linked immunosorbent assay specific for DS-sIL-6R. Release of this isoform was unaffected by ionomycin or TAPI, indicating that Ca2+ mobilization activates PC-sIL-6R generation, but not DS-sIL-6R. The divergent control of these sIL-6R isoforms indicates that they may independently influence the inflammatory response.

Immunohistochemical localization of different epitopes of advanced glycation end products in human atherosclerotic lesions

To better understand the role of advanced glycation end products (AGEs) in atherogenesis, we developed specific antibodies against different immunological epitopes of AGE structures, including Nepsilon-(carboxymethyl)lysine-protein adduct (CML) and a structure(s) other than CML (nonCML), and demonstrated the immunohistochemical localization of CML- and nonCML-epitopes in atherosclerotic lesions of human aorta, which were obtained at autopsy from 20 nondiabetic patients (12 males and eight females; mean age, 60.8+/-16.7 years). Monoclonal anti-CML antibody (6D12) recognized not only AGE-modified proteins, but also CML-modified proteins. On the other hand, polyclonal anti-nonCML antibody reacted to AGE-modified proteins, but not to CML-modified proteins. Both antibodies were unreactive to the early-stage products of glycation, including fructose-modified butyloxycarbonyl-lysine and fructose-epsilon-aminocaproic acid. Atherosclerotic lesions included diffuse intimal thickening (DIT), fatty streaks (FS), atherosclerotic plaques (AP) and complicated lesions. An immunohistochemical analysis showed both CML- and nonCML-epitopes to be found along the collagen fibers in DIT in subjects more than 40 years old, but not in subjects less than 40 years old. CML-epitopes accumulated mainly in the cytoplasm of macrophage/foam cells, while nonCML-epitopes accumulated exclusively in the extracellular spaces in FS. APs showed the CML-epitope stored macrophage/foam cells, and the accumulation of both CML- and nonCML-epitopes in the lipid-rich fibrous area. An immunohistochemical analysis with a monoclonal antibody against oxidized low density lipoprotein (FOH1a/DLH3) showed the presence of this antigen within the cytoplasm of the macrophage/foam cells in atherosclerotic lesions, which were also positive for the CML-epitopes. These findings thus suggest that the heterogeneous localization of AGEs in atherosclerotic lesions depends on their different epitopes, and that a close link, therefore, exists between the peroxidation of LDL and the formation of AGEs in atherosclerotic lesions.

Deceleration in the age pattern of mortality at older ages

The rate of mortality increase with age tends to slow down at very old ages. One explanation proposed for this deceleration is the selective survival of healthier individuals to older ages. Data on mortality in Sweden and Japan are generally compatible with three predictions of this hypothesis: (1) decelerations for most major causes of death; (2) decelerations starting at younger ages for more "selective" causes; and (3) a shift of the deceleration to older ages with declining levels of mortality. A parametric model employed to illustrate the third prediction relies on the distinction between senescent and background mortality. This dichotomy, though simplistic, helps to explain the observed timing of the deceleration.

Distribution of cathepsin E in the larval and adult organs of the bullfrog with special reference to the mature form in the larval fore-gut

The distibution of cathepsin E in several organs of the bullfrog, Rana catesbeiana, was analyzed at pre- and post-metamorphic stages by the acid proteinase assay, by visualization of enzyme activity on polyacrlamide fore-gut gels after electrophoresis and by immunoblotting with anti-cathepsin E serum. Cathepsin E was mainly distributed in the foregut at the larval stage and in the stomach, duodenum, large intestine and gall bladder at the post-metamorphic stage. In the larval fore-gut, a higher amount of the mature form of cathepsin E was observed in addition to the proform, but in other organs, including the stomach at the post-metamorphic stage, the mature form was barely detected. Developmental changes in the amount of cathepsin E were found in the digestive tract and the gall bladder by quantitative immunoblotting analysis. Finally, the larval fore-gut was stained immunohistochemically with anti-cathepsin E serum and the surface epithelium gave a strong immunoreactive signal.

High-level production of alternatively spliced soluble interleukin-6 receptor in serum of patients with adult T-cell leukaemia/HTLV-I-associated myelopathy

We have previously shown, using human T-cell lymphocytotrophic virus-I (HTLV-I)-infected cell lines, that soluble interleukin-6 receptor (sIL-6R) is generated through an alternative splicing mechanism. In this study, we examined human sera for the presence of alternatively spliced soluble IL-6R (AS-sIL-6R). We produced a monoclonal antibody (mAb) recognizing the unique sequence of AS-sIL-6R peptide, generated by an altered reading frame. We also made recombinant AS-sIL-6R protein in Spodoptera frugiperda-9 (Sf-9) cells carrying baculovirus, which encoded altered sIL-6R or conventional IL-6R cDNA. mAbs specifically recognized AS-sIL-6R, but not conventional IL-6R, as demonstrated by Western blot analyses, fluorescence-activated cell sorter, immunofluorescence analyses and enzyme-linked immunosorbent assay (ELISA). We adapted an ELISA system and used it for detection of altered sIL-6R in sera from 23 healthy persons, 12 patients with adult T-cell leukaemia (ATL) and 13 patients with HTLV-I-associated myelopathy (HAM). Serum levels of AS-sIL-6R were 6.4 or 6.1 times greater in ATL (28.7+/-20.4 ng/ml, P<0.0001) and in HAM patients (27.5+/-12.1 ng/ml, P<0.0001) than in healthy individuals (4.5+/-2.1 ng/ml). High levels of AS-sIL-6R were also observed in plasma from rheumatoid arthritis patients and in persons with elevated levels of alanine aminotransferase (ALT), antinuclear antibody (ANA), or alpha-fetoprotein (AFP). However, in human immunodeficiency virus-1 (HIV-1), hepatitis B virus (HBV) or hepatitis C virus (HCV)-infected individuals, AS-sIL-6R levels were not elevated. In this study, we confirmed that AS-sIL-6R is indeed present in human sera. These observations suggest that alternative splicing of IL-6R mRNA is of consequence in ATL, HAM and in some autoimmune diseases. The HTLV-I-infected T cells appeared to play an important role in AS-sIL-6R production.

Induction of murine macrophage growth by oxidized low density lipoprotein is mediated by granulocyte macrophage colony-stimulating factor

We have examined whether certain secreted factor(s) is involved in oxidized low density lipoprotein (Ox-LDL)-induced murine macrophage growth. An antibody against granulocyte-macrophage colony-stimulating factor (GM-CSF) effectively inhibited Ox-LDL-induced macrophage growth by >80%. Ox-LDL as well as phospholipase A2-treated acetylated LDL enhanced mRNA levels and protein release of GM-CSF from macrophages, while neither acetylated LDL nor lysophosphatidylcholine (lyso-PC) showed such effects. The maximal induction of GM-CSF by Ox-LDL was noted at 4 h, followed by a time-dependent decrease to a basal level within 24 h. Ox-LDL-induced macrophage growth was inhibited by 75% by replacement of the culture medium at 24 h by a fresh medium containing the same concentration of Ox-LDL, when GM-CSF had already returned to the basal level. Thus, a cytokine(s) other than GM-CSF is also expected to participate in Ox-LDL-induced macrophage growth in a later phase. The Ox-LDL-induced GM-CSF release was inhibited by calphostin C, a protein kinase C inhibitor, and was significantly reduced in macrophages from the knockout mice lacking class A, type I and type II macrophage scavenger receptors (MSR-AI/AII). These results taken together indicate that effective endocytosis of lyso-PC of Ox-LDL by macrophages through MSR-AI/AII and subsequent protein kinase C activation have led to GM-CSF release into the medium which may play a priming role in conjunction with other cytokines in Ox-LDL-induced macrophage growth.

Expression of ACAT-1 protein in human atherosclerotic lesions and cultured human monocytes-macrophages

The acyl coenzyme A:cholesterol acyltransferase (ACAT) gene was first cloned in 1993 (Chang et al, J Biol Chem. 1993;268:20747-20755; designated ACAT-1). Using affinity-purified antibodies raised against the N-terminal portion of human ACAT-1 protein, we performed immunohistochemical localization studies and showed that the ACAT-1 protein was highly expressed in atherosclerotic lesions of the human aorta. We also performed cell-specific localization studies using double immunostaining and showed that ACAT-1 was predominantly expressed in macrophages but not in smooth muscle cells. We then used a cell culture system in vitro to monitor the ACAT-1 expression in differentiating monocytes-macrophages. The ACAT-1 protein content increased by up to 10-fold when monocytes spontaneously differentiated into macrophages. This increase occurred within the first 2 days of culturing the monocytes and reached a plateau level within 4 days of culturing, indicating that the increase in ACAT-1 protein content is an early event during the monocyte differentiation process. The ACAT-1 protein expressed in the differentiating monocytes-macrophages was shown to be active by enzyme assay in vitro. The high levels of ACAT-1 present in macrophages maintained in culture can explain the high ACAT-1 contents found in atherosclerotic lesions. Our results thus support the idea that ACAT-1 plays an important role in differentiating monocytes and in forming macrophage foam cells during the development of human atherosclerosis.

The very low- and intermediate-density lipoprotein fraction isolated from apolipoprotein E-knockout mice transforms macrophages to foam cells through an apolipoprotein E-independent pathway

Apolipoprotein E (apoE)-knockout mice develop severe atherosclerosis associated with high levels of very low-density lipoprotein (VLDL) and intermediate-density lipoprotein (IDL) in plasma. To investigate the atherogenic role of VLDL and IDL, the lipoprotein fraction containing both VLDL and IDL (apoEko-VLDL/IDL) was isolated from plasma of apoE-knockout mice by ultracentrifugation, and its interaction with macrophages was studied. When peritoneal macrophages obtained from apoE-knockout mice were incubated with apoEko-VLDL/IDL, the level of cellular cholesteryl esters (CE) increased with the concentration of apoEko-VLDL/IDL. The level of cellular cholesteryl [3H]oleate formed reached 15.1 nmol/mg of cell protein upon incubation with 50 microg/mL apoEko-VLDL/IDL for 18 h, which was an 8.4-fold increase over the corresponding level induced by low-density lipoprotein (LDL). The cellular CE mass was also significantly increased by apoEko-VLDL/IDL. Morphologically, after exposure to apoEko-VLDL/IDL, macrophages became strongly stained with Sudan black B. The total binding of [125I]apoEko-VLDL/IDL to macrophages was effectively replaced by more than 80% by an excess of the unlabeled ligand. Specific binding, calculated by subtracting the nonspecific binding from the total binding, exhibited a saturation pattern. Similar results were obtained with cell association and degradation experiments. In addition, the endocytic degradation of [125I]apoEko-VLDL/IDL was partially inhibited by LDL, whereas acetyl-LDL did not show any effect. These results indicated that apoEko-VLDL/IDL in its unmodified form produced significant CE accumulation in macrophages through a specific and apoE-independent pathway. This pathway may explain, in part, the mechanisms of foam cell formation in arterial walls and the subsequent development of atherosclerosis in apoE-knockout mice.

Overview and initial results of the very long baseline interferometry space observatory programme

High angular resolution images of extragalactic radio sources are being made with the Highly Advanced Laboratory for Communications and Astronomy (HALCA) satellite and ground-based radio telescopes as part of the Very Long Baseline Interferometry (VLBI) Space Observatory Programme (VSOP). VSOP observations at 1.6 and 5 gigahertz of the milli-arc-second-scale structure of radio quasars enable the quasar core size and the corresponding brightness temperature to be determined, and they enable the motions of jet components that are close to the core to be studied. Here, VSOP images of the gamma-ray source 1156+295, the quasar 1548+056, the ultraluminous quasar 0014+813, and the superluminal quasar 0212+735 are presented and discussed.

Goblet cell carcinoid of the appendix endoscopically diagnosed and examined with p53 immunostaining

We report a case of a 62-year-old woman with goblet cell carcinoid of the appendix. She was admitted to our hospital in September 1994 after the discovery of liver tumors. After admission, a tumor in the right kidney and multiple tumors in the liver were found. She was diagnosed with renal cell cancer and metastasis to the liver and underwent excision of the kidney and enucleation of the largest liver tumor. Histological examination revealed that the liver tumor was a metastatic carcinoid tumor. As carcinoid tumors have frequently been found in the appendix, endoscopic examination was performed and a lesion was found in the appendix by colonoscopy. As predicted, the biopsy specimen was a carcinoid tumor, and she underwent an appendectomy. Histologically, the tumor was a goblet cell carcinoid. Goblet cell carcinoid is a rather rare neoplasm that has the histologic features of both carcinoids and adenocarcinoma. Forty-two cases of goblet cell carcinoid of the appendix have been reported thus far in Japan. However, few were diagnosed via endoscopic examination before surgical operation. We also carried out an immunohistochemical study with anti p53 antibody on the goblet cell carcinoid tumor of the appendix. Most tumor cells were strongly positive, while in three benign carcinoid tumors investigated simultaneously they were negative. These findings suggest that goblet cell carcinoid has an aggressive phenotype compared with benign carcinoid tumors.

Localization of identified advanced glycation end-product structures, N epsilon(carboxymethyl)lysine and pentosidine, in age-related inclusions in human brains

The recent identification of age-related accumulation of advanced glycation end-products (AGE) of the Maillard reaction in neurons and vessels of the human brain suggests the involvement of AGE in the aging process. A variety of inclusions such as lipofuscin granules, corpora amylacea, Hirano bodies, granulovacuolar degenerations and ubiquitin-positive granular structures are found in the aged human brain. These age-related inclusions contain insoluble and non-degradable proteins. Advanced glycation end-product-modified proteins are also known to be insoluble and protease resistant. The similarity between proteins in such inclusions and AGE-modified proteins suggests the presence of AGE in inclusions. To investigate this possibility, the presence of two known AGE structures, N epsilon(carboxymethyl)lysine (CML) and pentosidine, was examined in age-related inclusions. Immunohistochemical examination of the medial temporal area of brain tissues obtained at autopsy from seven non-demented elderly individuals demonstrated positive reactions in lipofuscin granules and corpora amylacea but not in other inclusions for anti-CML and anti-pentosidine antibodies. As CML and pentosidine are glycoxidation products among AGE, the results suggest that glycation and/or oxidation may be involved in the formation of lipofuscin granules and corpora amylacea.

Accumulation of Nsigma-(carboxy-methyl)lysine and changes in glomerular extracellular matrix components in Otsuka Long-Evans Tokushima fatty rat: a model of spontaneous NIDDM

Increases in extracellular matrix (ECM) and changes in its components have been documented in the glomeruli of diabetic nephropathy. Advanced glycation end products formed by glycoxidation have been shown to induce the synthesis of ECM components and transforming growth factor beta (TGF-beta), suggesting that advanced glycation end products may be involved in the etiology of imbalance of ECM components in diabetic glomerulosclerosis. The Otsuka Long-Evans Tokushima Fatty (OLETF) rat is an inbred strain that spontaneously develops non-insulin-dependent diabetes mellitus which progresses to diabetic glomerulosclerosis. Nepsilon-(carboxymethyl)lysine (CML) is known to be formed by glycoxidation. To clarify the involvement of glycoxidation in diabetic nephropathy, we examined the localization of CML, ECM components, and TGF-beta1 in the glomeruli of OLETF rats. The amounts of alpha3(IV) collagen, type VI collagen, and fibronectin were significantly increased in the glomeruli of OLETF rats, whereas the heparan sulfate proteoglycan levels were decreased. After 6 months of age, CML levels were significantly increased in the mesangial area of the glomeruli in these animals. The overexpression of TGF-beta1 preceded the increase in glomerular ECM components. The present study demonstrated that the accumulation of CML precedes the changes of glomerular ECM components in the glomeruli during the course of diabetic nephropathy, suggesting that glycoxidation may be one of the major causes of diabetic glomerulosclerosis.

Immunohistochemical localisation of advanced glycation end products in pulmonary fibrosis

AIM

To investigate the presence and distribution of advanced glycation end products (AGE) in pulmonary fibrosis.

METHODS

Lung tissue samples obtained from seven necropsy cases with idiopathic pulmonary fibrosis and seven with normal pulmonary parenchyma were examined immunohistochemically with a monoclonal antibody specific for AGE: 6D12. We also tested three cases with diffuse alveolar damage.

RESULTS

All the specimens from cases with pulmonary fibrosis and diffuse alveolar damage showed strong AGE expression on macrophages. Lung specimens from normal parenchyma showed positive AGE immunoreactivity on macrophages from only two of seven cases.

CONCLUSIONS

These findings suggest that AGE modified proteins accumulate in alveolar macrophages in patients with diffuse alveolar damage and idiopathic pulmonary fibrosis.

[Usefulness of magnetic resonance imaging for evaluation of therapeutic efficacy of bone metastases from bladder cancer: a case report]

A 70-year-old man had a prostate-invading bladder cancer with multiple bone metastases. The bladder cancer seemed to have metastasized via the vertebral vein system because there was no metastasis in other organs. Transurethral resection of bladder tumor was performed followed by one course of M-VAC (methotrexate, vinblastine, doxorubicin) therapy and MEP (methotrexate, etoposide and cisplatin) therapy. After chemotherapy, magnetic resonance imaging (MRI) of the spine revealed further progression of disease, although bone scintigraphy did not, and the patient died of disease.

Immunochemical approaches to AGE-structures: characterization of anti-AGE antibodies

Recent immunological approaches have greatly helped broaden our understanding of the biomedical significance of advanced glycation end products (AGEs) in aging and age-enhanced disease processes. Recently, Nepsilon-(carboxymethyl) lysine (CML), one of the glycoxidation products of AGEs, was demonstrated to be a major immunological epitope among AGEs. In the subsequent study, we characterized 13 different polyclonal anti-AGE antibodies and showed that these antibodies could be classified into three groups (Groups I, II and III). Group I was specific for CML and both Group II and Group III were specific for other epitopes (non-CML). Time-course study suggested that the epitope of Group II was formed earlier than that of Group III. In the present study, we prepared two monoclonal anti-AGE antibodies (2A2 and 3A3) whose epitope structures appeared to be closely related to Group III and Group II, respectively. The result indicates that AGE-proteins express at least two major non-CML epitopes.

Glycolaldehyde-modified low density lipoprotein leads macrophages to foam cells via the macrophage scavenger receptor

It was shown that proteins modified with advanced glycation end products (AGE) are effectively endocytosed by macrophages or macrophage-derived cells in vitro, and immunohistochemical studies involving anti-AGE antibodies demonstrated the accumulation of AGE-modified proteins (AGE-proteins) in macrophage-derived foam cells in human atherosclerotic lesions in situ, suggesting the involvement of AGE-modified LDL in the atherogenic process in vivo. To examine this suggestion, LDL was modified with glycolaldehyde, a highly reactive intermediate of the Maillard reaction. Physicochemically, glycolaldehyde-modified LDL (GA-LDL) was characterized by increases in negative charge, fluorescence intensity, and reactivity to anti-AGE antibodies, properties highly similar to those of AGE-proteins. The cellular interaction of GA-LDL with mouse peritoneal macrophages showed that GA-LDL was specifically recognized and endocytosed, followed by lysosomal degradation. The endocytic uptake of GA-LDL by these cells was competitively inhibited by acetylated LDL (acetyl-LDL), and the endocytic degradation of acetyl-LDL was also competed for by GA-LDL. Furthermore, incubation of GA-LDL with these macrophages and Chinese hamster ovary cells overexpressing the macrophage scavenger receptor (MSR), but not with peritoneal macrophages from MSR-knockout mice, led to the intracellular accumulation of cholesteryl esters (CE). These results raised the possibility that AGE-modified LDL, if available in situ, is taken up by macrophages mainly via MSR and then contributes to foam cell formation in early atherosclerotic lesions.

The multiple roles of macrophage scavenger receptors (MSR) in vivo: resistance to atherosclerosis and susceptibility to infection in MSR knockout mice

Both type I and type II MSRs are integral membrane proteins containing a collagenous domain and elicit an extraordinarily wide range of ligand binding capability. They were found during the search for the molecule(s) responsible for the accumulation of modified LDL during atherogenesis. However, all prior the evidence relating to their physiological and pathophysiological roles in vivo had been indirect. Targeted disruption of the MSR gene results in a reduction in the size of atherosclerotic lesions in an apo E deficient animal. Macrophages from MSR deficient mice exhibit a marked decrease in modified LDL uptake in vitro, whereas modified LDL clearance from plasma remains normal, suggesting that there are alternative mechanisms for the uptake of modified LDL from the circulation. In addition, MSR knockout mice are more susceptible to L. monocytogenes and HSV-1 infection, indicating a role for MSR in host defense against various pathogens.

Elevated serum levels of the soluble form of gp130, the IL-6 signal transducer, in HTLV-1 infection and no involvement of alternative splicing for its generation

By using an ELISA, increased levels of the soluble form (sgp130) of gp130, the IL-6 signal transducer, were detected in the sera of various HTLV-1-associated conditions (HC, ATL, HAM) as compared to normal healthy individuals. Sgp130 levels seemed to be correlated with disease severity. The 94 KD of sgp130 was specifically precipitated in the sera of HTLV-1-infected patients as revealed by Western blot analysis. A reverse transcriptase (RT)-polymerase chain reaction (PCR) method was used to detect the message for transmembrane (TM) lacking gp130 in mRNA isolated from peripheral blood mononuclear cells (PBMCs) of patients infected with or without HTLV-1 and those of various hematopoietic cell lines. Two PCR products, 648 and 507 bp were observed in the PBMCs from HTLV-1-infected patients. But the 507 by PCR product was not detected in the PBMCs from normal healthy individuals and HTLV-1-positive cell lines although the 648 bp product was equally expressed. A nucleotide sequence analysis of the 507 bp fragment showed deletion of the 141 bp at the region spanning from nucleotide 1702 (G) to 1842 (T) of the 648 bp product that matched completely with a conventional gp130 molecule. This deleted region was located upstream of the transmembrane (TM) domain, but not within the TM region itself. However, no frame shift was observed. These results indicate that the generation of sgp130 may not be due to an alternative splicing mechanism.

Immunohistochemical study of human advanced glycation end-products (AGE) and growth factors in cardiac tissues of patients on maintenance dialysis and with kidney transplantation

Cardiovascular disease is one of the most common complications of dialysis and renal transplant patients, and high levels of AGE are present in end-stage renal failure. To address the potential involvement of AGE and growth factors in the pathophysiology of cardiovascular complications, we performed immunostaining using cardiac tissues from autopsy cases of patients on maintenance dialysis (10 cases), long-term surviving renal transplant patients with functioning grafts (8 cases), control subjects with normal renal function (7 cases) and non diabetic subjects with mild renal insufficiency (8 cases). We used two types of AGE-antibodies, 6D12 [monoclonal anti-AGE antibody, recognizing N epsilon-(carboxymethyl) lysine(CML)-modified AGE] (oxidative AGE) and non-CML-PA [polyclonal, not recognizing CML], and antibodies against PDGFs, PDGF receptors and TGF beta. Positive 6D12 staining was observed in the coronary arterial walls and in macrophages. The accumulation of 6D12-reactive AGE in the coronary arterial walls of maintenance dialysis patients was significantly greater than that of control subjects (p < 0.05). Renal transplantation significantly reduced this accumulation (p < 0.05). On the other hand non-CML-PA mainly detected AGE in intracardiac arterioles and neural tissues. There was little difference in the accumulation of non-CML-AGE among the four groups. PDGFs and PDGF receptors were mainly detected in vascular endothelial cells and infiltrating cells of cardiac tissues of renal transplant patients, but not of maintenance dialysis patients. TGF beta was not detected in cardiovascular tissue of transplant patients. Our results indicated that the accumulation of oxidative AGE (CML-AGE) in the cardiac vascular tissue is one of the factors for cardiovascular complications of maintenance dialysis patients, and also that renal transplantation has a reducing effect on CML-AGE accumulation. PDGFs may be involved in the cardiovascular complications after renal transplantation.

Relationship of epidermal growth factor binding capacity to histopathologic features and prognosis in human renal cell carcinoma

We studied the association between epidermal growth factor (EGF) binding capacity and histopathologic features or prognosis in human renal cell carcinoma (RCC) by Scatchard analysis in 67 patients. EGF binding capacity was significantly greater in metastatic than in nonmetastatic tumors, and in nuclear grade 3 than nuclear grade 1 tumors. Multivariate analysis revealed that tumor stage, nuclear grade, EGF binding capacity, and tumor size significantly correlated with overall survival. These results suggest that EGF binding may be an important determinant of prognosis in patients with RCC.