Advanced glycation end products (AGEs) are a heterogeneous group of protein and lipids to which sugar residues are covalently bound. AGE formation is increased in situations with hyperglycemia (e.g., diabetes mellitus) and is also stimulated by oxidative stress, for example in uremia. It appears that activation of the renin-angiotensin system may contribute to AGE formation through various mechanisms. Although AGEs could nonspecifically bind to basement membranes and modify their properties, they also induce specific cellular responses including the release of profibrogenic and proinflammatory cytokines by interacting with the receptor for AGE (RAGE). However, additional receptors could bind AGEs, adding to the complexity of this system. The kidney is both: culprit and target of AGEs. A decrease in renal function increases circulating AGE concentrations by reduced clearance as well as increased formation. On the other hand, AGEs are involved in the structural changes of progressive nephropathies such as glomerulosclerosis, interstitial fibrosis, and tubular atrophy. These effects are most prominent in diabetic nephropathy, but they also contribute to renal pathophysiology in other nondiabetic renal diseases. Interference with AGE formation has therapeutic potential for preventing the progression of chronic renal diseases, as shown from data of animal experiments and, more recently, the first clinical trials.

Background:We investigated whether ghrelin is present in human saliva, is produced by salivary glands, and physiologic consequences of these findings. Methods: Expression of ghrelin and specific receptor mRNA was determined by PCR. Proteins were identified by immunoblotting and size-exclusion fast protein liquid chromatography (FPLC) with consecutive RIA. Specific RIAs were used for quantification of salivary total and bioactive ghrelin. Distribution of ghrelin was investigated by immunohistochemistry in cryosections of the salivary glands. The effect of ghrelin on incorporation of 5-bromo-2-deoxyuridine as a measure of cell proliferation was investigated in primary oral keratinocytes. Results: Ghrelin is produced by the salivary glands. The hormone was identified in saliva and glands by immunoblotting and by FPLC fractionation of saliva. Immunohistochemistry demonstrated ghrelin distribution in the salivary glands. The receptor was also produced by the glands and by oral keratinocytes and was shown to be functional. Comparison of total ghrelin values for healthy individuals (body mass index, 18 -27 kg/m 2 ) showed significantly lower concentrations in saliva than in serum (P <0.01). The correlation between both matrices was r 2 ‫؍‬ 0.56 (P <0.001) with a negative correlation to body mass index (r 2 ‫؍‬ 0.314; P <0.01). Bioactive acylated ghrelin was also present in saliva. Incubation of keratinocytes with ghrelin led to signifi-

We developed a model of spontaneously high human remn hypertensron m the rat by producing two transgemc strains, one for human angrotensmogen with the endogenous promoter and one for human renm with the endogenous promoter Neither transgemc strain was hypertensive These strains were then crossed, producing a double transgemc strain The double transgemc rats, both males and females, developed severe hypertension (mean systolic pressure, 200 mm Hg) and died after a mean of 55 days If untreated The rats had a human plasma rerun concentratton of 2692381 (+SD) ng angtotensm I (Ang I)/mL per hour, plasma renm actrvrty of 1772176 ng Ang I/mL per hour, rat angtotensmogen concentratron of 1 492 1 pg Ang I/mL, and human angtotensmogen concentration of 78239 pg Ang I/mL (n=49) Control rats had plasma remn actrvrty of 3 7t3.9 ng Ang I/mL per hour and rat angrotensmogen of 1 3220 16 /lg Ang I/mL Angrotensmogen transgene expression by RNase protectton assay was ubrqmtously present but most prominent m liver Renm transgene expression was htgh m kidney but absent m liver The rats featured severe cardiac hypertrophy, with mcreased cross section of cardromyocytes but little myocardtal fibrosts The kidneys showed atrophrc tubules, thickened vessel walls, and increased mterstttmm Both the angtotensm-converting enzyme mhtbttor hsmopnl and the specific human remn mhtbttor remrkrren lowered blood pressure to normal values Double transgemc mice have been developed that exhibit features quite similar to those described here, their gene expressions are stmtlar The spectfictty of rodent and human renm 1s stmrlarly documented Although many elegant physrologtcal studtes can now be done m mice, rats nevertheless offer flexrbdrty, partrcularly m terms of detailed cardiac and renal phystology and pharmacology We conclude that this double transgemc strain wtll facthtate srmultaneous mvesttgatton of genettc and pathophystologtcal aspects of remn-induced hypertension The fact that human renm can be studied m the rat IS a unique feature of this model (Hypertensron. 1997 When infused wrth hREN, this otherwrse normotensrve rat becomes severely hypertensive 1 Under the condrtton of chronic mfusron wrth hREN, the rat is smtable for study of hREN mhtbitors, whrch otherwrse have no effect in the rat.2 However, for study of the human renm-angrotensm system m the rat for perrods ranging from weeks to months, the mimpump mfuston model has maJor shortcommgs, making rt not suitable for studying mechanisms of cardiac hypertrophy, hypertensive nephrosclerosrs, or central nervous system damage To ctrcumvent this problem, we have crossed the TGR(hAOGEN) with a TGR harboring the hREN gene. This TGR(hREN)IOJ was developed m Japan In- Correspondence to Frredrrch C Luft, Franz Volhard Clnuc, Wrltberg Strasse 50, 13122 Berlin, FRG E-marl fcluft@ orton rz mdc-berlm de 0 1997 Amerrcan Heart Assocratron, Inc formation on this rat has not yet been published Offspring from this cross harbor both transgenes and therefore have all the necessary components of the hu...

Angiotensin II (AngII) mediates proinflammatory properties by activating NF-B transcription factor nuclear translocation and inducing the expression of chemokines. For examination of whether AngII modulates the expression of Toll-like receptor 4 (TLR4), a key element of the innate immune system that senses LPS, mouse mesangial cells (MMC) were treated with AngII. AngII upregulated TLR4 mRNA and protein in MMC, and this effect was mediated through AngII type 1 receptors. Reporter gene experiments indicate that an activating protein-1 (AP-1) as well as an E-26 specific sequence (Ets) binding site in the TLR4 promoter are responsible for the AngII-stimulated transcriptional activity of the TLR4 gene. Preincubation of MMC with AngII enhanced LPS-induced NF-B activation and chemokine expression. Immunohistochemical analyses revealed that double-transgenic rats that overexpressed human renin and angiotensinogen expressed higher levels of glomerular TLR4 compared with normal Sprague-Dawley rats. In vivo, infusion with AngII but not with norepinephrine into rats for 7 d also enhanced glomerular NF-B activation after systemic application of LPS, suggesting that the effects are independent of concomitantly induced hypertension. Together, these observations suggest that AngII leads to an activation of the innate immune system by a novel mechanism involving the upregulation of TLR4. Our data contribute to a better understanding of how exogenous infections may trigger renal autoimmune processes, particularly in pathophysiologic situations with high renal AngII concentrations. Because TLR4 binds endogenous ligands (e.g., extracellular matrix components) in addition to microbial products, AngII-mediated upregulation of TLR4 also could be relevant for the development of inflammation in many noninfectious renal diseases.

Hearing and touch are genetically related, and people with excellent hearing are more likely to have a fine sense of touch and vice versa.

Abstract-To elucidate the local effects of renin in the coronary circulation, we examined local angiotensin (Ang) I and II formation, as well as coronary vasoconstriction in response to renin administration, and compared the effects with exogenous infused Ang I. We perfused isolated hearts from rats overexpressing the human angiotensinogen gene in a Langendorff preparation and measured the hemodynamic effects and the released products. We also investigated cardiac Ang I conversion, including the contribution of non-angiotensin-converting enzyme-dependent Ang II-generating pathways. Finally, we studied Ang I conversion in vitro in heart homogenates. Renin and Ang I infusion both generated Ang II. Ang II release and vasoconstriction continued after renin infusion was stopped, even though renin disappeared immediately from the perfusate. In contrast, after Ang I infusion, Ang II release and coronary flow returned to basal levels. Ang I conversion (Ang II/Ang I ratio) was higher after renin infusion (0. ). We conclude that renin can be taken up by cardiac or coronary vascular tissue and induces long-lasting local Ang II generation and vasoconstriction. Locally formed Ang I was converted more effectively than infused Ang I. Furthermore, the comparison of in vivo and in vitro Ang I conversion suggests that in vitro assays may underestimate the functional contribution of angiotensin-converting enzyme to intracardiac Ang II formation. (Circ Res. 1998;82:13-20.) Key Words: transgenic rat Ⅲ angiotensin Ⅲ human renin Ⅲ cardiac renin-angiotensin system Ⅲ chymase-like activity A ngiotensin II plays a major role in cardiovascular homeostasis, including the regulation of blood pressure, salt balance, and tissue remodeling. Ang I and Ang II are produced not only in the blood compartment but also locally in tissues. In fact, the tissues are the major site of Ang I and Ang II formation, and the release of locally formed Ang II contributes to the circulating levels of these peptides.1-3 All the components of the renin-angiotensin system have been detected in the heart, 4-6 indicating that the heart is not only a target but also a site of endocrine or paracrine Ang II formation. Local Ang II formation may result from the interaction of renin and AOGEN produced within the vessel wall or from the uptake and retention of renin and AOGEN from the plasma, on the cell surface, or the interstitial fluid. [7][8][9][10][11][12] Many studies addressing the cardiac effects of Ang II have been performed by infusing Ang I or Ang II into the coronary circulation. In vivo, the cascade leading to Ang formation is stimulated by the enzyme renin. Even though it seems not to be produced by cardiac tissue, renin may be taken up to react locally with its substrate, AOGEN.There is a current controversy regarding the major pathway for Ang II formation in the human heart. Although ACE inhibitors are highly effective in treating hypertension-associated cardiac hypertrophy and congestive heart failure, [13][14][15] studies with ACE inhibitors have raised th...

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We tested the hypothesis that changes in angiotensin-converting enzyme (ACE) gene expression can regulate the rate of local vascular angiotensin II (Ang II) production. We perfused isolated rat hindlimbs with an artificial medium and infused renin and Ang I via the perfusate. Ang I and II were measured by radioimmunoassay. We then increased ACE gene expression and ACE levels in the rat aorta by producing two-kidney, one clip (2K1C) hypertension for 4 weeks. Gene expression was measured by RNAse protection assay, and ACE activity in the vessel wall was measured by the Cushman-Cheung assay. Angiotensin I infusion at 1, 10, 100, and 1000 pmol/mL led to 371 +/- 14 (+/-SEM), 3611 +/- 202, 44,828 +/- 1425, and 431,503 +/- 16,439 fmol/mL Ang II released, respectively, from the hindlimbs (r = .98, P < .001). Thus, the conversion rate did not change across four orders of magnitude, and the system was not saturable under these conditions. In 2K1C hindlimbs, Ang I infusion (0.5 pmol/mL) resulted in increased Ang II generation (157 +/- 16 versus 123 +/- 23 fmol/mL, P = .014 at minute 10) compared with controls. ACE gene expression and ACE activity were increased in 2K1C hindlimbs compared with controls (36 +/- 4 versus 17 +/- 1 mU/mg protein, P < .001). Ang II degradation in the two groups did not differ. To investigate the conversion of locally generated Ang I, we infused porcine renin (0.5 milliunits per mL) into 2K1C and control hindlimbs. Despite markedly higher Ang I release in sham-operated than in 2K1C rats (71 +/- 8 versus 37 +/- 6 pmol/mL, P = .008 at minute 12), Ang II was only moderately increased (36 +/- 3 versus 25 +/- 6 pmol/mL, P = .12 at minute 12). This difference between 2K1C rats and controls reflected a higher rate of conversion in 2K1C rats. Thus, Ang I conversion in the rat hindlimb is linear over a wide range of substrate concentrations and occurs at a fixed relationship. Nevertheless, increased ACE gene expression and ACE activity in the vessel wall lead to an increase in the conversion of Ang I to Ang II. We conclude that local ACE gene expression and ACE activity can influence the local rate of Ang II production.