Hyperphosphataemia sensitizes renally impaired rats to the profibrotic effects of gadodiamide.

BACKGROUND AND PURPOSE: Hyperphosphataemia is common in patients with nephrogenic systemic fibrosis (NSF). NSF has been linked to administration of gadolinium (Gd) chelates (GCs) and elevated serum phosphate levels accelerate the release of Gd from linear, non-ionic GCs but not macrocyclic GCs. Hence, we determined whether hyperphosphataemia is a cofactor or risk factor for NSF by investigating the role of hyperphosphataemia in renally impaired rats. EXPERIMENTAL APPROACH: Firstly, the clinical, pathological and bioanalytical consequences of hyperphosphataemia were investigated in subtotal nephrectomized (SNx) Wistar rats following i.v. administration of the non-ionic, linear GC gadodiamide (5 × 2.5 mmol·kg(-1) ·day(-1) ). Secondly, the effects of several GCs were compared in these high-phosphate diet fed rats. Total Gd concentration in skin, femur and plasma was measured by inductively coupled plasma mass spectrometry (ICP-MS) and free Gd(3+) in plasma by liquid chromatography coupled to ICP-MS. Relaxometry was used to measure dissociated Gd in skin and bone. KEY RESULTS: Four out of seven SNx rats fed a high-phosphate diet administered gadodiamide developed macroscopic and microscopic (fibrotic and inflammatory) skin lesions, whereas no skin lesions were observed in SNx rats treated with saline, the other GCs and free ligands or in the normal diet, gadodiamide-treated group. Unlike the other molecules, gadodiamide gradually increased the r(1) relaxivity value, consistent with its in vivo dissociation and release of soluble Gd. CONCLUSIONS AND IMPLICATIONS: Hyperphosphataemia sensitizes renally impaired rats to the profibrotic effects of gadodiamide. Unlike the other GCs investigated, gadodiamide gradually dissociates in vivo. Our data confirm that hyperphosphataemia is a risk factor for NSF.

Magnetic resonance imaging of ruptured plaques in the rabbit with ultrasmall superparamagnetic particles of iron oxide.

BACKGROUND: Magnetic resonance imaging (MRI) enhanced with ultrasmall superparamagnetic particles of iron oxide (USPIO) has previously been evaluated in hyperlipidemic rabbits. The aim of this study was therefore to compare USPIO in ruptured and non-ruptured arteries in an atherosclerotic rabbit model. METHODS: Atherosclerotic-like lesions were induced by the combination of endothelial abrasion and high-cholesterol diet in iliac rabbit arteries (n = 16). Rupture of atherosclerotic lesions was realized by oversized balloon angioplasty in one iliac artery, whereas the contralateral artery was used as control. USPIO (ferumoxtran-10: 1 mmol Fe/kg) was administered immediately (n = 10) or 28 days (n = 6) after injury. MRI and histological analysis were performed 7 and 35 days after injury and in control arteries. RESULTS: In vivo MRI analysis showed extended susceptibility artifact with transluminal signal loss in all ruptured arteries 7 days after injury. In contrast, hyposignal was reduced 35 days following injury (i.e. after healing), and absent in non-ruptured arteries. Similarly, histological analysis of iron uptake was significantly increased 7 days after injury compared to healed-ruptured and control arteries. CONCLUSIONS: Accumulation ofUSPIO is significantly increased in ruptured as compared to non-ruptured arteries in the atherosclerotic rabbit model.

Pharmacological postconditioning with the phytoestrogen genistein.

Estrogens are known to activate the phosphatidyl-inosityl 3-kinase (PI3K)/Akt pathway, which is central in the cardioprotection afforded by ischemic postconditioning. Therefore, our goal was to investigate whether a phytoestrogen, genistein, could induce a pharmacological postconditioning and to investigate potential mechanisms. We used low doses of genistein in order to avoid tyrosine kinases inhibition. Thus, pentobarbital-anesthetized rabbits underwent a coronary artery occlusion followed by 4 h of reperfusion. Prior to reperfusion, they randomly received an i.v. injection of either saline (Control), 100 or 1000 microg/kg of genistein (Geni(100) and Geni(1000), respectively), and 10 or 100 microg/kg of 17beta-estradiol (17beta(10) and 17beta(100), respectively). Infarct size (IS, % area at risk) was significantly reduced in Gen(100), Gen(1000) and 17beta(100) but not in 17beta(10) (6+/-2, 16+/-5, 12+/-3 and 29+/-7%, respectively) vs. Control (35+/-4%). A significant decrease in the percentage of TUNEL-positive nuclei within infarcted area was observed in Gen(100) and 17beta(100) vs. Controls. The estrogen receptor antagonist fulvestrant (1 mg/kg i.v.) and the PI3K inhibitor wortmaninn (0.6 mg/kg) abolished the cardioprotective effect of genistein. Western blots also demonstrated an increase in Akt posphorylation in Gen(100). In the same group, in vitro mitochondrial swelling studies demonstrated a significant inhibition of calcium-induced opening of mitochondrial transition pore vs. Controls. In conclusion, genistein exerts pharmacological postconditioning with a similar potency as 17beta-estradiol through a pathway involving activation of the estrogen receptor, of PI3K/Akt and mitochondrial preservation. Therefore, genistein should not be only considered as an inhibitor of tyrosine kinase but also as a cardioprotective estrogen.

UT-B1 urea transporter is expressed along the urinary and gastrointestinal tracts of the mouse.

Selective transporters account for rapid urea transport across plasma membranes of several cell types. UT-B1 urea transporter is widely distributed in rat and human tissues. Because mice exhibit high urea turnover and are the preferred species for gene engineering, we have delineated UT-B1 tissue expression in murine tissues. A cDNA was cloned from BALB/c mouse kidney, encoding a polypeptide that differed from C57BL/6 mouse UT-B1 by one residue (Val-8-Ala). UT-B1 mRNA was detected by RT-PCR in brain, kidney, bladder, testis, lung, spleen, and digestive tract (liver, stomach, jejunum, colon). Northern blotting revealed seven UT-B1 transcripts in mouse tissues. Immunoblots identified a nonglycosylated UT-B1 protein of 29 kDa in most tissues and of 36 and 32 kDa in testis and liver, respectively. UT-B1 protein of gastrointestinal tract did not undergo N-glycosylation. Immunohistochemistry and in situ hybridization localized UT-B1 in urinary tract urothelium (papillary surface, ureter, bladder, and urethra), prominently on plasma membranes and restricted to the basolateral area in umbrella cells. UT-B1 was found in endothelial cells of descending vasa recta in kidney medulla and in astrocyte processes in brain. Dehydration induced by water deprivation for 2 days caused a tissue-specific decrease in UT-B1 abundance in the urinary bladder and the ureter.

Proteinuria and tubulointerstitial lesions in lupus nephritis.

BACKGROUND: Response of the renal tubules to proteinuria is implicated in progression of renal disease. Experimentally, proteinuria causes increased tubular synthesis of macrophagic and other chemokines, with increased tubular cellular proliferation and apoptosis, leading to interstitial inflammation and fibrosis. Clinically, diminution of proteinuria leads to the slowing of progression, but whether this leads to reduction in tubular lesions has not been directly demonstrated in humans. METHODS: Initial (Bx1) and systematic six-month biopsies (Bx2) from 71 patients with lupus nephritis were studied, with a subset of 34 biopsies also stained for proliferating cell nuclear antigen (PCNA), the macrophage marker PGM1, and cytokeratins (AE1/AE3), and morphometric cell and tubular profile counts performed. RESULTS: Positive correlations were found between increasing levels of proteinuria and the following light microscopic parameters: tubular epithelial pyknosis, tubular epithelial nuclear "activation," tubular lumenal macrophages, interstitial inflammation and fibrosis, but not with tubulointerstitial immunofluorescence. Significant positive correlations also were found with the following immunohistochemical parameters: PCNA in epithelial cells (r = 0.74) and tubular luminal cells (r = 0.47); tubular lumenal macrophages (r = 0.63) and tubular epithelial cells with acquired PGM1 staining (r = 0.36); and pyknotic tubular epithelial cells (r = 0.47). All showed strong correlations with serum creatinine (S(Cr)) as well. All were reduced at Bx2, generally in parallel to the reduction in proteinuria. Tubulointerstitial immune deposits appear to play only a minor role in the development of tubular epithelial lesions and the progression of renal disease in lupus. They show only limited correlation with SCr and no correlation with proteinuria. By multiple regression, they are not associated with tubular epithelial lesions, interstitial inflammation or interstitial fibrosis at either biopsy, whereas tubular epithelial lesions are strongly associated with interstitial inflammation at Bx1 and with interstitial fibrosis at Bx2. Cytokeratin correlated strongly with S(Cr) (r = 0.53, P = 0.002) but not with proteinuria (r = 0.27, NS), and was the sole immunohistochemical parameter to increase at Bx2. It appears to be a sensitive marker for tubular atrophy. CONCLUSIONS: In this study both proteinuria and SCr showed a hierarchy of correlations with morphologic variables: Tubular epithelial cell changes> tubular macrophages> interstitial inflammation> interstitial fibrosis, corresponding to current experimental models, but not previously demonstrated in humans.

Inflammation is probably not a prerequisite for renal interstitial fibrosis in normoglycemic obese rats.

We examined the role of inflammation in the development of renal interstitial fibrosis in Zucker obese rats, which rapidly present kidney lesions in the absence of hypertension and hyperglycemia. Type I and III collagens were quantified using a polarized light and computer-assisted image analyzer. The expression of mRNA encoding matrix components, adhesion molecules, chemokines, and growth factors was followed by RT-PCR. The presence of synthesized proteins as well as lymphocytes and macrophages was determined by immunohistochemistry. Interstitial fibrosis developed in two phases. The first phase occurred as early as 3 mo and resulted from a neosynthesis of type III collagen and fibronectin and a reduction of extracellular matrix catabolism, in parallel with an overexpression of transforming growth factor-beta(1) and in the absence of any lymphocyte or macrophage infiltration. After 6 mo, interstitial fibrosis worsened with a large accumulation of type I collagen, concomitantly with a large macrophage infiltration. Thus inflammation cannot explain the onset of interstitial fibrosis that developed in young, insulinoresistant, normoglycemic, obese Zucker rats but aggravated this process afterward.

Neonatal induction of tolerance to T(h)2-mediated autoimmunity in rats.

Brown-Norway (BN) rats are highly susceptible to drug-induced immune dysregulations and when injected with mercuric chloride (HgCl(2)) or sodium aurothiopropanolsulfonate (ATPS), they develop a syndrome characterized by a polyclonal B cell activation depending upon CD4(+) T(h)2 cells that recognize self-MHC class II molecules. Since peripheral tolerance of T(h)2 cells might be crucial in the prevention of immunological manifestations such as allergy, establishing conditions for inducing tolerance to HgCl(2)- or ATPS-mediated immune manifestations appeared to be of large interest. We report here that BN rats neonatally injected with HgCl(2): (i) do not develop the mercury disease, (ii) remain resistant to HgCl(2)-induced autoimmunity at 8 weeks of age and later, provided they are regularly exposed to HgCl(2), (iii) are still susceptible to ATPS-induced immune manifestations, and (iv) exhibit spleen cells that adoptively transfer tolerance to HgCl(2)-induced autoimmunity in naive, slightly irradiated, syngeneic recipients. These findings demonstrate that dominant specific tolerance can be neonatally induced using a chemical otherwise responsible for T(h)2-mediated autoimmunity.

Early glomerular macrophage recruitment in streptozotocin-induced diabetic rats.

Diabetic glomerulosclerosis is defined by increased glomerular extracellular matrix (ECM) that is mainly synthesized by mesangial cells that underwent an activation mediated by cytokines and growth factors from various cellular origins. In this study, we tested whether macrophages could infiltrate the glomeruli and influence ECM synthesis in experimental diabetes. To test our hypothesis, we initially studied the dynamics of glomerular macrophage recruitment in streptozotocin-induced diabetic rats at days 1, 2, 4, 8, 15, and 30 by using quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) on isolated glomeruli and immunohistochemistry and morphometry. We then assessed the role of macrophages on the basis of the pharmacological modulation of their recruitment by insulin or ACE inhibitor treatments and by X-irradiation-induced macrophage depletion at days 8 and 30. Macrophages were recruited within the glomeruli at the very early phase of hyperglycemia by using RT-PCR CD14 detection from day 2 and by using ED1 immunohistochemistry from day 8. This glomerular macrophage infiltration was associated with an increase in alpha1-chain type IV collagen mRNA. In parallel, the diabetic glomeruli became hypertrophic with an increase in the mesangial area. Macrophage recruitment was preceded by or associated with an increased glomerular expression of vascular cell adhesion molecule 1, intracellular adhesion molecule 1, and monocyte chemoattractant protein 1, which contributes to monocyte diapedesis. Glomerular interleukin-1beta mRNA synthesis was also enhanced as early as day 1 and could be involved in the increase in ECM and adhesion molecule gene expressions. Insulin treatment and irradiation-induced macrophage depletion completely prevented the glomerular macrophage recruitment and decreased alpha1-chain type IV collagen mRNA and mesangial area in diabetic rats, whereas ACE inhibitor treatment had an incomplete effect. It can be concluded that in the streptozotocin model, hyperglycemia is followed by an early macrophage recruitment that contributes to the molecular and structural events that could lead to glomerulosclerosis. Therefore, besides direct stimulation of mesangial cells by hyperglycemia, macrophages recruited in the glomeruli during the early phase of hyperglycemia could secondarily act on mesangial cells.

Chronic blockade of NO synthase activity induces a proinflammatory phenotype in the arterial wall: prevention by angiotensin II antagonism.

Chronic blockade of NO production induces hypertension and early occlusive and fibrotic end-stage organ damage owing to vascular lesions in the brain, kidney, and heart. In this study, we evaluated the inflammatory phenotypic changes induced in the arterial wall by chronic N(G)-nitro-L-arginine methyl ester (L-NAME) administration and the effect of an angiotensin II receptor (AT1) antagonist, irbesartan, on these changes. For this purpose, 2 groups of rats received L-NAME in the drinking water (50 mg x kg(-1) x d(-1)) for 2 months. One group received no other treatment and the other was treated with irbesartan (10 mg x kg(-1) x d(-1)). A third group (controls) received neither L-NAME nor irbesartan. After 8 weeks, plasma, aortas, and left ventricles were sampled from all 3 groups. Expression of inducible NO synthase (iNOS) was evaluated at both the mRNA (quantitative reverse transcription-polymerase chain reaction) and the protein (Western blot and immunohistochemistry) level in the aorta. Expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) was evaluated by reverse transcription-polymerase chain reaction, Western immunoblotting, and immunohistochemistry; inflammatory cell infiltration by immunohistochemistry; and fibrosis by Sirius red staining. Chronic L-NAME administration induced the expression of iNOS in the aorta, which was localized in smooth muscle cells as shown by immunohistochemistry and NADPH diaphorase activity. ICAM-1 and VCAM-1 expression was also increased in aortas of L-NAME-treated rats. These phenotypic changes of the vascular wall were associated with inflammatory cell infiltration and fibrosis in the heart. All of these pathological phenomena were prevented by the angiotensin II antagonist irbesartan. The proinflammatory phenotypic changes of the vascular wall induced by blockade of NOS activity could be involved in the interaction between endothelial dysfunction and the development of arteriosclerosis.

Immunolocalization of the Na+/H+ exchanger isoform NHE2 in rat kidney.

Four Na+/H+ exchangers (NHE1 to NHE4) have been detected in the kidney. Renal NHE2 expression sites have not been fully established. We have raised rabbit antisera against an oligopeptide related to the amino acids 652 to 661 of rat NHE2. Western blot analysis of plasma membrane fractions isolated from rat renal cortex showed that affinity-purified anti-NHE2 antibody detected an 85-kDa protein in apical but not in basolateral membranes. The labeling of this 85-kDa protein was specifically blocked by preincubation of the antibody with its monomeric peptide, indicating specific recognition. Indirect immunolabeling was performed on sections of paraformaldehyde-fixed rat kidney embedded in paraffin. Strong staining was seen in the apical membrane of cortical thick ascending limbs, distal convoluted tubules, and connecting tubules. Much weaker apical staining was found in medullary thick ascending limbs of Henle. In the inner medulla, some thin limbs were intensively labeled by the anti-NHE2 antibody. No staining could be detected in any segments of the proximal tubule and collecting duct.

Podocytes undergo phenotypic changes and express macrophagic-associated markers in idiopathic collapsing glomerulopathy.

Collapsing glomerulopathy (CG), a severe form of focal segmental glomerulosclerosis (FSG), is characterized by tuft retraction and consolidation in numerous glomeruli and changes in podocyte morphology and topography. Other glomeruli are less affected. Collapsing glomerulopathy is also characterized by tubulointerstitial atrophy and fibrosis. The pathophysiology of the glomerular and tubulointerstitial lesions is poorly understood. We studied renal tissue of five Black and three White patients, all human immuno-deficiency virus (HIV) negative, with nephrotic syndrome, renal failure, and histological evidence of CG. Immunohistochemistry identified normal podocyte phenotypes by podocalyxin, vimentin and complement receptor 1 (CR1) labeling. Three monoclonal antibodies were used to further characterize podocyte epitopes: anti-CD68 clone KP1, anti-CD68 clone PG-M1 and anti-M130 clone M18 (Ber-MAC3). Light microscopy of collapsed glomeruli showed podocyte swelling, vacuolization, multinucleation, "cobblestone-like" alignment around the glomerular tuft, and pseudo-crescent formation in Bowman's space. In collapsed glomeruli, podocalyxin, vimentin and CR1 labeling tagged both normal and vacuolated podocytes still attached to the GBM, but labeling was not found in cobblestone-like podocytes or in podocytes detached from the GBM. Conversely, numerous podocytes undergoing detachment and shedding into Bowman's space expressed macrophagic-associated epitopes. Cells with macrophagic-associated epitopes clumped in cystically dilated tubules and were aligned in tubules of smaller caliber. Their appearance was that of viable cells. There was no morphologic indication that these cells expressing macrophage-associated antigens originated from outside the glomeruli or outside the tubules. We conclude that in CG podocytes detach from the GBM, lose their normal podocytic phenotype and acquire macrophage differentiation antigens. The presence of cells with such antigens in tubular lumens suggests that detached metaplastic podocytes progress along the tubule or, alternatively, that CG tubular cells also undergo metaplastic changes into macrophage-like cells.

Localization of elastin mRNA and TGF-beta1 in rat aorta and caudal artery as a function of age.

Several in vitro studies have previously demonstrated that the addition of TGF-beta to aortic smooth muscle cells or skin fibroblasts stimulates elastin synthesis. It is not clear however whether, in vivo, TGF-beta participates in the regulation of elastin synthesis, especially in physiological conditions. The aim of our study was to explore the localization of elastin mRNA and TGF-beta1 in the rat thoracic aorta (an elastic artery) and caudal artery (a muscular artery). Elastin mRNA was localized by in situ hybridization and quantified using Northern blot analysis. TGF-beta1 was detected using immunohistochemistry. The study was carried out as a function of age (rats of 3, 10, 20, and 30 months). We observed that TGF-beta1 immunoreactivity is present predominantly, but not exclusively, at the sites of elastin synthesis as determined by elastin mRNA detection: in smooth muscle cells in the aorta and in endothelial cells in the caudal artery. The ability of exogenously added TGF-beta1 (0.001-10 ng/ml) to modulate the steady-state levels of elastin mRNA in primary cultures of endothelial cells, smooth muscle cells, and fibroblasts isolated from the thoracic aorta was also studied. At the highest concentration used, elastin mRNA levels increased 5-fold in endothelial cells and 11-fold in smooth muscle cells. The demonstration that TGF-beta1 immunoreactivity is present at the sites of elastin synthesis in the thoracic aorta and in the caudal artery and the observation that TGF-beta1 induces an increase in elastin mRNA levels in cultured endothelial cells and smooth muscle cells suggest that TGF-beta1 may be implicated, at least in part, in the physiological regulation of elastin gene expression.

Lymphocytes in human atherosclerotic plaque exhibit the elastin-laminin receptor: potential role in atherogenesis.

The purpose of this immuno-histochemical study was to investigate if lymphocytes, present in the human atherosclerotic plaque, exhibit the elastin-laminin receptor. We showed recently that human activated lymphocytes in vitro express this receptor. Briefly, we demonstrated by immuno-localization experiments and by flow cytometry that this receptor is available on the cell surface of human activated lymphocytes, free to react with ligands and show capping. The activation of this receptor by elastin peptides triggers several cellular reactions of biological interest as shown previously such as chemotactic movement to an elastin peptide gradient, modulation of the biosynthesis of connective tissue macromolecules, increase of protease synthesis and release of free radicals (O2-., NO.) from mononuclear and endothelial cells, modifications of ion fluxes and also increase of cell proliferation. All these processes may contribute to the development of the atherosclerotic lesion. Two of the previously demonstrated cell reactions mediated by the receptor could be demonstrated also on PHA-stimulated human lymphocytes namely stimulation of cell proliferation and increase of elastase activity. We demonstrated in the present immuno-histological study that about 50-60% of lymphocytes of the human atherosclerotic plaque obtained by endarterectomy express the 67 kDa subunit of the elastin-laminin receptor confirming that the above described phenomena could contribute to the chronicity of the lesion.

Normal human immunoglobulins for intravenous use (IVIg) delay hyperacute xenograft rejection through F(ab')2-mediated anti-complement activity.

Xenotransplantation between discordant species leads to a hyperacute rejection mediated by natural antibodies, both of the IgG and IgM isotypes, activation of complement and endothelial cell activation. The combination of these mechanisms leads to a transplant survival of minutes to a few hours. Polyclonal human immunoglobulins for intravenous use (IVIg) from normal donors have proved effective in a number of antibody-mediated disorders, as well as in inflammatory disorders. We demonstrate that administration of IVIg in a guinea pig to rat model of cardiac xenografting can effectively delay hyperacute rejection. This effect is mediated by the F(ab')2 fragments of IVIg, and is correlated to an anti-complementary activity.

The immunogenicity of the extracellular matrix in arterial xenografts.

BACKGROUND: Determinants of xenograft immunogenicity are poorly characterized. We showed previously that decellularized arterial xenografts (DAXs) dilate, whereas decellularized arterial isografts (DAIs) and allografts do not, suggesting an interspecies, rather than an intraspecies, immunogenicity of the arterial extracellular matrix leading to chronic rejection. Now we have investigated the immunogenicity of the arterial extracellular matrix in xenografts and its impact on chronic injury (elastin lysis) and remodeling (graft dilation). METHODS: Diameter and elastin content were measured in DAIs and DAXs from hamster to rat (concordant combination) and guinea pig to rat (discordant combinations) at 8 weeks. We also characterized the immune effectors infiltrating DAIs and DAXs by immunohistochemistry after 6 hours to 4 weeks of implantation. Results were compared with nondecellularized isografts and xenografts. Last, the impact of the donor-recipient phylogenetic distance on monocyte-macrophage penetration into the media was assessed in three xenograft combinations. RESULTS: DAXs from guinea pig, but not from hamster, were aneurysmal at 8 weeks. Elastin lysis paralleled graft dilation. DAXs, but not DAIs, were infiltrated by monocytes, macrophages, T lymphocytes, and immunoglobulins. The donor-recipient combination did not affect the phenotype of the inflammatory infiltrate in DAXs, but it modified the kinetics of monocyte-macrophage penetration into the media. The absence of decellularization changed the inflammatory infiltrate phenotype (absence of macrophages) but had little impact on DAX injury and remodeling. CONCLUSIONS: DAX immunogenicity accounts for most of chronic arterial xenograft injury, which is modulated by the donor-recipient combination. The immunogenicity of arterial xenografts, unlike allografts, is supported by the extracellular matrix in addition to the cells and could influence the long-term fate of xenografts.

Cytomegalovirus (CMV) viremia and the CD4+ lymphocyte count as predictors of CMV disease in patients infected with human immunodeficiency virus.

We screened 192 patients infected with human immunodeficiency virus (HIV) to examine the relation between CD4+ lymphocyte counts and cytomegalovirus (CMV) viremia and the occurrence of CMV disease and subsequent duration of survival. When we stratified the viremic patients by CD4+ lymphocyte counts, the proportions were as follows: <50/mm3, 20 (25%) of 80 patients; 50-100/mm3, 2 (5.5%) of 36; 101-150/mm3, none of 14; and >150/mm3, 1 (1.5%) of 62. After a mean follow-up period of 8.5 months, 21 (11%) of 192 patients developed CMV disease. The probability of developing CMV disease at 6 months was 13% when the CD4+ lymphocyte count was <50/mm3, 3% when the CD4+ lymphocyte count was 50-100/mm3, and 0 when the CD4+ lymphocyte count was >100/mm3; this probability was 46% for viremic patients and 1% for nonviremic patients. In a multivariate analysis, CMV viremia was independently prognostic of CMV disease (relative risk, 22.03; 95% confidence interval, 6.49-78.97; P < .001), whereas a CD4+ lymphocyte count of <50/mm3 was not (P = .26). These results support the value of CMV viremia for predicting which HIV-infected patients are at risk of developing CMV disease and should therefore receive primary prophylaxis.

Inflammatory cells and myocardial fibrosis: spatial and temporal distribution in renovascular hypertensive rats.

OBJECTIVE: The fibroblasts producing collagen are co-localized with inflammatory cells in myocardial fibrosis areas of spontaneously hypertensive rats, suggesting that collagen overproduction in this model may be modulated by inflammatory cells. The present study extends these observations to the Goldblatt model of hypertension in which the renin-angiotensin system is activated. METHODS: Inflammatory cells were identified with monoclonal antibodies directed against macrophages (ED1+), T helper (CD4+) and cytotoxic lymphocytes (CD8+), and MHC class II-expressing cells (Ia+). The alkaline phosphatase-anti-alkaline phosphatase (APAAP) immuno-staining technique was used. A new computer-assisted morphometric method was utilized to quantify the inflammatory infiltrate in each cardiac compartment with polarized-light microscopy. Cells responsible for the collagen synthesis were identified by in situ hybridization. The collagen content was estimated by morphometry on left ventricle sections stained with Sirius red, and by biochemical quantification of the hydroxyproline concentration. RESULTS: Computer-assisted morphometry under polarized light was well suited to quantify inflammatory cells labeled by the APAAP technique. Inflammatory cells were co-localized with collagen-synthesizing fibroblasts. The main inflammatory cells were CD4+ lymphocytes > Ia+ > ED1+ > CD8+ cells. These cell densities were increased in hypertensive rats in all cardiac areas compared to control rats except for IA+ cells which were concentrated in microscars. Macrophage density was correlated with plasma renin activity. The inflammatory cell density which best correlated with fibrosis was macrophage density, and which best correlated with systolic blood pressure was macrophage and T helper lymphocyte densities. CONCLUSIONS: One can speculate that the correlation between macrophage density and blood pressure as well as with plasma renin activity may indicate that angiotensins and/or elevation of blood pressure could participate in the initial signalling which may mobilize inflammatory cells. These inflammatory cells could promote fibrosis by releasing mediators such as growth factors or cytokines which act upon fibroblasts.

Presensitization accelerates allograft arteriosclerosis.

Transplant arteriosclerosis is the major factor influencing allograft survival after the first year posttransplantation. The host's immunologic response is one of the principal effectors responsible for the constitution of this vascular wall lesion, but the effector pathway and the factors influencing the immune injury are not clear. In a rat abdominal aortic allograft model, we used a skin priming method to study the influence of sensitization on the occurrence of vascular wall lesions. Primed rats developed transplant arteriosclerosis lesions involving medial decellularization and intimal proliferation before the 21st day, whereas naive animals had the same lesions at 2 months posttransplantation. A significant difference between primed and naive rats was found for medial thickness (48.00 +/- 2.85 microm versus 79.34 +/- 2.55 microm, P<0.001) and smooth muscle cell content (160 +/- 28 cell/mm versus 466 +/- 19 cell/mm, P<0.001) at 21 days posttransplantation, and intimal hyperplasia was seen in primed animals at that time, whereas it was not observed in naive rats until the 60th day. The immune profile in naive and primed animals was different. The immune cells infiltrating the arterial wall in naive rats, were principally macrophages and CD8+ T-lymphocytes. No Ig or complement deposition was detected. IgG and complement activated fraction were present in the media of primed animals as early as the fifth day posttransplantation and CD4+ T lymphocytes were the dominant immune cell population. In conclusion, sensitization influences the immune mechanisms responsible for the development of transplant arteriosclerosis and alters the rate of its evolution.