Intense Macrophage Infiltration Research Articles

Molecular Signature of Antibody-Mediated Chronic Vasculopathy in Heart Allografts in a Novel Mouse Model

Cardiac allograft vasculopathy (CAV) limits the long-term success of heart transplants. Generation of donor-specific antibodies (DSAs) is associated with increased incidence of CAV clinically, but mechanisms underlying development of this pathology remain poorly understood. Major histocompatibility complex-mismatched A/J cardiac allografts in B6.CCR5-/- recipients have been reported to undergo acute rejection with little T-cell infiltration, but intense deposition of C4d in large vessels and capillaries of the graft accompanied by high titers of DSA. This model was modified to investigate mechanisms of antibody-mediated CAV by transplanting A/J hearts to B6.CCR5-/- CD8-/- mice that were treated with low doses of anti-CD4 monoclonal antibody to decrease T-cell-mediated graft injury and promote antibody-mediated injury. Although the mild inhibition of CD4 T cells extended allograft survival, the grafts developed CAV with intense C4d deposition and macrophage infiltration by 14 days after transplantation. Development of CAV correlated with recipient DSA titers. Transcriptomic analysis of microdissected allograft arteries identified the Notch ligand Dll4 as the most elevated transcript in CAV, associated with high versus low titers of DSA. More importantly, these analyses revealed a differential expression of transcripts in the CAV lesions compared with the matched apical tissue that lacks large arteries. In conclusion, these findings report a novel model of antibody-mediated CAV with the potential to facilitate further understanding of the molecular mechanisms promoting development of CAV.

Kidney Allograft Recipient Absence of Myeloperoxidase Decreases Donor-Specific Antibody Titers and Attenuates Antibody-Mediated Allograft Rejection

Abstract The incidence of antibody-mediated rejection (AMR) in clinical kidney transplants is increasingly observed. We have reported that strong donor-specific antibody (DSA) responses are induced in B6.CCR5−/−mice transplanted with complete MHC mismatched A/J kidney allografts and that NK cells play a critical role in acute injury and graft failure. Since this acute AMR is accompanied by intense macrophage infiltration into the allograft, we tested the role of recipient-derived myeloperoxidase (MPO) production on kidney allograft survival. B6.CCR5−/−and B6.CCR5−/−MPO−/−mice were transplanted with complete MHC mismatched A/J kidney grafts. Allografts were rejected between days 18 and 25 post-transplant in B6.CCR5−/−recipients but not until days 46–54 in B6.CCR5−/−MPO−/− recipients. DSA titers in B6.CCR5−/−MPO−/−recipients were 4–5 fold lower than those induced in the B6.CCR5−/− recipients. There was also a 60% decrease in the number of donor-reactive T cells producing IFN-g in the spleens of the B6.CCR5−/−MPO−/− vs. B6.CCR5−/−recipients on day 7 post-transplant. Despite the extended survival, qPCR analyses indicated slight increases in mRNA encoding TNFa, IL-6 and FasL in kidney allografts on day 14 post-transplant in B6.CCR5−/−MPO−/− vs. B6.CCR5−/−recipients as well as the pro-fibrogenic factors P-selectin and connective tissue growth factor on day 50 post-transplant. These results suggest MPO regulates the magnitude of the DSA and T cell response in kidney transplant recipients and that the decreased DSA titers attenuate acute AMR but induce the indolent development of interstitial fibrosis and glomerular injury that will eventually lead to graft dysfunction and failure at later times.

Bioengineered H-Ferritin Nanocages for Quantitative Imaging of Vulnerable Plaques in Atherosclerosis.

Inflammation and calcification concomitantly drive atherosclerotic plaque progression and rupture and are the compelling targets for identifying plaque vulnerability. However, current imaging modalities for vulnerable atherosclerotic plaques are often limited by inadequate specificity and sensitivity. Here, we show that natural H-ferritin nanocages radiolabeled with technetium-99m (99mTc-HFn) can identify and accurately localize macrophage-rich, atherosclerotic plaques in living mice using combined SPECT and CT. Focal 99mTc-HFn uptake was observed in the atherosclerotic plaques with multiple high-risk features of macrophage infiltration, active calcification, positive remodeling, and necrosis on histology and in early active ongoing lesions with intense macrophage infiltration. The uptake of 99mTc-HFn in plaques enabled quantitative measuring of the dynamic changes of inflammation during plaque progression and anti-inflammation treatment. This strategy lays the foundation of using bioengineered endogenous human ferritin nanocages for the identification of vulnerable and early active plaques as well as potential assessment of anti-inflammation therapy.

Regulated C-C motif ligand 2 (CCL2) in luteal cells contributes to macrophage infiltration into the human corpus luteum during luteolysis.

Intense macrophage infiltration is observed during luteolysis in various animals including women; however, we still do not know how macrophage infiltration into the human corpus luteum (CL) during luteolysis is regulated. In this study, we examined the expression, localization and regulation of an important chemokine for the recruitment of monocyte/macrophage lineages, C-C motif ligand 2 (CCL2), in the human CL across the luteal phase and in cultured human luteinized granulosa cells (LGCs), with special reference to the number of infiltrating macrophages and luteal cell function. CCL2 mRNA increased in the non-functional regressing CL during menstruation (P < 0.01), corresponding to an elevated mRNA expression of a macrophage-derived cytokine, tumor necrosis factor (TNF), and an increased number of infiltrating macrophages positively stained with a macrophage marker, CD68. CCL2 protein was immunohistochemically localized to the cytoplasm of granulosa-lutein and theca-lutein cells, and CCL2 mRNA was significantly reduced by hCG both in vivo (P < 0.05) and in vitro (P < 0.01). CCL2 was also down-regulated by luteotrophic prostaglandin (PG) E (P < 0.0001), but up-regulated by luteolytic PGF (P < 0.05) in vitro. Administration of TNF significantly enhanced the CCL2 mRNA expression in cultured LGCs (P < 0.01). A greater abundance of infiltrating macrophages were found around granulosa-lutein cells lacking 3β-HSD or PGE synthase (PGES) immunostaining. CCL2 mRNA expression was negatively correlated with both HSD3B1 and PGES, suggesting that locally produced progesterone and PGE suppress macrophage infiltration into the CL. Taken together, the infiltration of macrophages in the human CL is regulated by endocrine and paracrine molecules via regulation of the CCL2 expression in luteal cells.

High-Dose Intravenous Immunoglobulin (IVIG) Adjuvant Therapy for Cell-Mediated Pancreas Transplant Rejection

High-Dose Intravenous Immunoglobulin (IVIG) Adjuvant Therapy for Cell-Mediated Pancreas Transplant Rejection

Macrophage imaging by USPIO-enhanced MR for the differentiation of infectious osteomyelitis and aseptic vertebral inflammation

The purpose of this study was to prospectively evaluate USPIO-enhanced MR imaging for the differentiation of vertebral infectious osteomyelitis and sterile inflammation. Vertebral osteomyelitis and sterile vertebral inflammation were induced in two groups of six rabbits each. MRI examinations were performed including unenhanced and gadolinium-enhanced fat-saturated SE T1w sequences. Once endplate enhancement was observed on the T1 gadolinium-enhanced MR sequence, a second MRI examination (SE T1w sequence) was performed 24 h after USPIO administration (45 micromol Fe/kg). MR imaging was correlated with histopathological findings (macrophage immunostaining and Perls Prussian blue staining). On gadolinium-enhanced T1 sequences, a significant SNR increase in vertebral endplates was present in both groups without significant difference between the two groups (P = 0.26). On USPIO-enhanced T1 sequences, a significant SNR increase was only observed in the infection group (P = 0.03) with a significant difference in SNR between the infection and the sterile-inflammation groups (P = 0.002). Infected areas presented replacement of bone marrow by an intense macrophage infiltration, some being iron-loaded. Sterile inflammation showed a replacement of bone marrow by inflammatory tissue with only rare macrophages without any Perls blue staining. USPIO-enhanced MR imaging can distinguish infectious osteomyelitis from sterile vertebral inflammation due to different macrophage distributions in the two lesions.

C3G overexpression in glomerular epithelial cells during anti-GBM-induced glomerulonephritis

The guanine nucleotide exchange factor C3G, along with the CrkII adaptor protein, mediates GTP activation of the small GTPase proteins Rap1 and R-Ras, facilitating their activation of downstream signaling pathways, which had been found to be important in the pathogenesis of glomerulonephritis. We found that expression of C3G protein was upregulated in glomerular epithelial cells in an experimental model of accelerated anti-GBM antibody-induced glomerulonephritis expression. To determine the consequence of its increased expression, we transfected C3G (using adenoviral constructs) into cultured glomerular epithelial cells and measured the activated forms (i.e., GTP-bound) forms of Rap1 and R-Ras. Activation of Rap1 was not affected by C3G; however, the basal level of GTP-bound R-Ras was decreased. Further, C3G over-expression enhanced the activation of R-Ras in response to endothelin. Overexpression of C3G also led to a significant reduction in glomerular epithelial cell spreading and decreased the cells' E-cadherin expression and augmented their migration. We found that C3G was overexpressed in accelerated anti-GBM antibody-induced glomerulonephritis and suggest that this modulates glomerular epithelial cell morphology and behavior.

Serum interleukin-6 is elevated in symptomatic carotid bifurcation disease

The levels of circulating proinflammatory cytokines may express the extent of the inflammatory response and their participation in plaque progression and rupture needs to be evaluated. We aimed to investigate differences in circulating levels of proinflammatory cytokines and in plaque infiltration by macrophages between patients undergoing carotid endarterectomy for symptomatic and asymptomatic carotid atherosclerotic disease. One hundred nineteen patients (91 men and 28 women; mean age 66 +/- 8 years; range 42-83 years) who underwent carotid endarterectomy for significant (>70%) carotid bifurcation stenosis were enrolled in this study. Patients were characterized as symptomatic (n = 62) or asymptomatic (n = 57) after neurological examination. Serum levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), IL-1beta, serum amyloid A (SAA), and high-sensitivity C-reactive protein (hs-CRP) were evaluated. Macrophage infiltration of the plaque was assessed quantitatively from endarterectomy specimens using the monoclonal antibody CD68. Serum IL-6 levels were significantly higher in patients with symptomatic compared with those with asymptomatic carotid disease (3.3 [2.0-6.5] pg/ml vs 2.5 [1.9-4.1] pg/ml, P = 0.02). TNF-alpha, IL-1beta, SAA, and hs-CRP levels did not differ significantly between the two groups. Symptomatic patients had also more intense macrophage accumulation in the carotid plaque compared with asymptomatic patients (0.6 +/- 0.1% vs 0.4 +/- 0.1%, P < 0.001). Although there were correlations between the levels of the different inflammatory markers, there were no correlation between any of them and the extent of plaque macrophage infiltration. Patients with symptomatic carotid atherosclerotic disease have elevated serum IL-6 levels compared with asymptomatic patients. Symptomatic patients have also more intense macrophage infiltration of the atherosclerotic plaque suggesting that inflammatory process may contribute to the destabilization of the carotid plaque.

Ischemic Central Necrosis in Pockets of Transplanted Myoblasts in Nonhuman Primates: Implications for Cell-Transplantation Strategies

Several cell-transplantation strategies implicate the injection of cells into tissues. Avascular accumulations of implanted cells are then formed. Because the diffusion of oxygen and nutrients from the surrounding tissue throughout the implanted cell accumulations may be limited, central ischemic necrosis could develop. We analyzed this possibility after myoblast transplantation in nonhuman primates. Macaca monkeys were injected intramuscularly with different amounts of myoblasts per single site. These sites were sampled 1 hr later and at posttransplantation days 1, 3, 5, and 7 and analyzed by histological techniques. One day posttransplantation, the largest pockets of implanted cells showed cores of massive necrosis. The width of the peripheral layer of living cells was approximately 100-200 microm. We thus analyzed the relationship between the amount of myoblasts injected per site and the volume of ischemic necrosis. Delivering 0.1 x 10(6) and 0.3 x 10(6) myoblasts did not produce ischemic necrosis; pockets of 1 x 10(6), 3 x 10(6), 10 x 10(6), and 20 x 10(6) myoblasts exhibited, respectively, a mean of 2%, 9%, 41%, and 59% of central necrosis. Intense macrophage infiltration took place in the muscle, invading the accumulations of necrotic cells and eliminating them by posttransplantation days 5 to 7. The desire to create more neoformed tissue by delivering more cells per injection site is confronted with the fact that the acute survival of the implanted cells is restricted to the peripheral layer that can profit of the diffusion of oxygen and nutriments from the surrounding recipient's tissue.

Spontaneous development of intestinal and colonic atrophy and inflammation in the carnitine-deficient jvs (OCTN2 −/−) mice

Carnitine is essential for transport of long-chain fatty acids into mitochondria for their subsequent β-oxidation, but its role in the gastrointestinal tract has not been well described. Recently several genetic epidemiologic studies have shown strong association between mutations in carnitine transporter genes OCTN1 and OCTN2 and a propensity to develop Crohn’s disease. This study aims to investigate role of carnitine and β-oxidation in the GI tract. We have studied the gastrointestinal tract effects of carnitine deficiency in a mouse model with loss-of-function mutation in the OCTN2 carnitine transporter. juvenile visceral steatosis (OCTN2 −/−) mouse spontaneously develops intestinal villous atrophy, breakdown and inflammation with intense lymphocytic and macrophage infiltration, leading to ulcer formation and gut perforation. There is increased apoptosis of jvs (OCTN2 −/−) gut epithelial cells. We observed an up-regulation of heat shock factor-1 (HSF-1) and several heat shock proteins (HSPs) which are known to regulate OCTN2 gene expression. Intestinal and colonic epithelial cells in wild type mice showed high expression and activity of the enzymes of β-oxidation pathway. These studies provide evidence of an obligatory role for carnitine in the maintenance of normal intestinal and colonic structure and morphology. Fatty acid oxidation, a metabolic pathway regulated by carnitine-dependent entry of long-chain fatty acids into mitochondrial matrix, is likely essential for normal gut function. Our studies suggest that carnitine supplementation, as a means of boosting fatty acid oxidation, may be therapeutically beneficial in patients with inflammation of the intestinal tract.

Vasculite e padrão de panbronquiolite difusa no lúpus eritematoso sistémico – Caso clínico

Visceral involvement in systemic lupus erythematosus (SLE) extends beyond renal and cutaneous management. Pleuro-pulmonary lesions have been recognised and diffuse alveolar damage and hemorrhage are the most difficult patterns to control. Pulmonary compromise in clinical evolution of SLE differs from children to adults, both in morphological patterns and in clinical presentation, depending on immunocompetence and the treatment prescribed.A 16-year-old boy presented asthenia, malaise and bilateral cervical painless adenopathies understood as EBV infection as serological EBV IgG, IgM and EBNA were positive. The symptoms persisted for eight months when discrete erythematous and desquamative nasal and malar rash expressed together with persistent fever, dispnoea and bibasilar crackles. Lymph node and pulmonary biopsi-ses were performed.Lymph node presented follicular hyperplasia and LMP1 (EBV) immunostaining was negative. In lung biopsy bronchovascular lesions were consistent with vasculitis and bronchiolitis due to intense macrophage infiltration, validated with CD68 antibody and intra-alveolar macrophages were also present with septal compromise; LMP1 (EBV) positive cells were not visualized.The lung pattern seen in CAT as diffuse micronodules all over the lung parenchyme resolved after corticos-teroid therapy. The diagnosis of SLE was confirmed by ANA, anti-dsDNA, anti-nDNA and anti-histones positivity.To the best of our knowledge this is the first reported case of pulmonary SLE involvement with vasculitis and diffuse panbronchiolitis – like pattern as the first clinical sign of the disease.Rev Port Pneumol 2007; XIII (2): 267-274

Vasculite e padrão de panbronquiolite difusa no lúpus eritematoso sistémico – Caso clínico

Visceral involvement in systemic lupus erythematosus (SLE) extends beyond renal and cutaneous management. Pleuro-pulmonary lesions have been recognised and diffuse alveolar damage and hemorrhage are the most difficult patterns to control. Pulmonary compromise in clinical evolution of SLE differs from children to adults, both in morphological patterns and in clinical presentation, depending on immunocompetence and the treatment prescribed.A 16-year-old boy presented asthenia, malaise and bilateral cervical painless adenopathies understood as EBV infection as serological EBV IgG, IgM and EBNA were positive. The symptoms persisted for eight months when discrete erythematous and desquamative nasal and malar rash expressed together with persistent fever, dispnoea and bibasilar crackles. Lymph node and pulmonary biopsises were performed.Lymph node presented follicular hyperplasia and LMP1 (EBV) immunostaining was negative. In lung biopsy bronchovascular lesions were consistent with vasculitis and bronchiolitis due to intense macrophage infiltration, validated with CD68 antibody and intra- alveolar macrophages were also present with septal compromise; LMP1 (EBV) positive cells were not visualized.The lung pattern seen in CAT as diffuse micronodules all over the lung parenchyme resolved after corticosteroid therapy. The diagnosis of SLE was confirmed by ANA, anti-dsDNA, anti-nDNA and anti-histones positivity.To the best of our knowledge this is the first reported case of pulmonary SLE involvement with vasculitis and diffuse panbronchiolitis – like pattern as the first clinical sign of the disease.

Tubulointerstitial macrophage infiltration in a patient with hypokalemic nephropathy and primary Sjögren’s syndrome

We report a case of hypokalemic nephropathy associated with primary Sjögren's syndrome (SS). The patient presented with profound and persistent hypokalemia secondary to distal renal tubular acidosis (RTA). A renal biopsy exhibited tubular degeneration, marked interstitial fibrosis and intense macrophage infiltration. Hypokalemia has been reported to induce macrophage infiltration in experimental animal models but not in humans. This is the first report of intense tubulointerstitial macrophage infiltration in a patient with hypokalemic nephropathy associated with SS.

Thymidine phosphorylase expression in tumour cells and tumour response to capecitabine plus docetaxel chemotherapy in non-small cell lung cancer

Background: Thymidine phosphorylase (TP) is the key enzyme for capecitabine activation in tumour cells. Aims: To examine whether TP expression in tumour cells and stroma is predictive of the tumour...

Temporal changes in matrix metalloproteinase expression and inflammatory response associated with cardiac rupture after myocardial infarction in mice

We previously found that male mice with myocardial infarction (MI) had a high rate of cardiac rupture, which generally occurred at 3 to 5 days after MI. Since matrix metalloproteinases (MMPs) play an important role in infarct healing, tissue repair and extracellular matrix (ECM) remodeling post-MI, we studied the temporal relationship of MMP expression and inflammatory response to cardiac rupture after acute MI. Male C57BL/6J mice were subjected to MI (induced by ligating the left anterior descending coronary artery) and killed 1, 2, 4, 7 or 14 days after MI. MMP-2 and MMP-9 activity in the heart were measured by zymography. Collagen content was measured by hydroxyproline assay. We found that after MI, MMP-9 activity increased as early as 1 day and reached a maximum by 2-4 days, associated with a similar increase in neutrophil and macrophage infiltration in the infarct area. MMP-2 started to increase rapidly within 4 days, reaching a maximum by 7 days and remaining high even at 14 days. Intense macrophage infiltration appeared by 4 days after MI and then gradually decreased within 7 to 14 days. Collagen content was unchanged until 4 days after MI, at which point it increased and remained high thereafter. Our data suggest that in mice, overexpression of MMP-2 and MMP-9 (possibly expressed mainly by neutrophils and macrophages) may lead to excessive ECM degradation in the early phase of MI, impairing infarct healing and aggravating early remodeling which in turn causes cardiac rupture.

Innate immune responses to LPS in mouse lung are suppressed and reversed by neutralization of GM-CSF via repression of TLR-4.

The innate immune inflammatory response to lipopolysaccharide (LPS, an endotoxin) is essential for lung host defense against infection by gram-negative bacteria but is also implicated in the pathogenesis of some lung diseases. Studies on genetically altered mice implicate granulocyte-macrophage colony-stimulating factor (GM-CSF) in lung responses to LPS; however, the physiological effects of GM-CSF neutralization are poorly characterized. We performed detailed kinetic and dose-response analyses of the lung inflammation response to LPS in the presence of the specific GM-CSF-neutralizing antibody 22E9. LPS instilled into the lungs of BALB/c mice induced a dose-dependent inflammation comprised of intense neutrophilia, macrophage infiltration and proliferation, TNF-alpha and matrix metalloproteinase release, and macrophage inflammatory protein-2 induction. The neutralization of anti-GM-CSF in a dose-dependent fashion suppressed these inflammatory indexes by 85% when given before or after LPS or after repeat LPS challenges. Here we report for the first time that the physiological expression of Toll-like receptor-4 in lung is reduced by anti-GM-CSF. We observed that lower Toll-like receptor-4 expression correlated with a similar decline in peak TNF- levels in response to endotoxin. Consequently, sustained expression of key inflammatory mediators over 24 h was reduced. These data expand the understanding of the contribution of GM-CSF to innate immune responses in lung and suggest that blocking GM-CSF might benefit some lung diseases where LPS has been implicated in etiology.

The changing pattern of HIV neuropathology in the HAART era.

Highly active antiretroviral treatment (HAART), which has been available for most AIDS patients in France since 1996, has resulted in a dramatic improvement of the progression of the disease. From the survey of our series of 343 brains with acquired immunodeficiency syndrome (AIDS) from patients who died between 1985 and 2002, we found both quantitative and qualitative changes in the pattern of human immunodeficiency virus (HIV) neuropathology. Quantitatively, despite a dramatic decrease in the number of autopsies, brain involvement remained a major cause of death. There was an overall decrease in incidence of cerebral toxoplasmosis, cytomegalovirus encephalitis (CMVE), and HIV encephalitis (HIVE), for which successful treatment is available. This contrasted with the unchanged incidence of progressive multifocal leukoencephalopathy (PML) and malignant non-Hodgkin lymphomas (MNHL). However, when looking closer at the 3 last years, the incidence of diseases affecting patients with severe immunodepression (CMVE, PML, and MNHL) decreased between 2000 and 2002, whereas infections occurring in patients with milder immunodeficiency, toxoplasmosis, varicella-zoster encephalitis (VZVE), or herpes simplex virus encephalitis (HSVE) became more frequent. In addition, we found uncommon types of brain infection such as BK virus encephalitis or general paresis. Finally, we described new variants of HIVE: severe leukoencephalopathy with intense perivascular macrophage and lymphocyte infiltration, possibly due to an exaggerated response from a newly reconstituted immune system, and chronic "burnt out" forms of HIVE as VZVE, toxoplasmosis, or PML, possibly associated with prolonged survival, in which neither inflammation nor organisms could be detected. These findings are compared with those reported in other neuropathological studies from different developed countries.

Macrophage colony-stimulating factor expression and macrophage accumulation in renal allograft rejection.

Studies of infiltrating cells from acutely rejecting renal allografts show that a high proportion of these cells are macrophages, and early macrophage infiltration is a poor prognostic sign for transplant survival. Macrophage colony-stimulating factor (M-CSF), produced by tubular and mesangial cells, has been associated with macrophage infiltration and proliferation in experimental and human kidney diseases. We investigated the expression of M-CSF in a model of acute rejection. Lewis rats underwent bilateral nephrectomies and received an orthotopic Dark Agouti allograft or Lewis isograft. Animals received cyclosporine (10 mg/kg/day) from day 0 to day 3 and were killed at days 4, 8, or 14 after transplantation. Macrophages (ED1+) and T cells (W3-13+) were identified by immunohistochemistry, and M-CSF expression was identified by Northern blotting and in situ hybridization. Isografts had normal renal function without histological evidence of rejection. Allografts exhibited a moderate infiltrate at day 4 but progressed to severe rejection at day 14, with elevated serum creatinine level and severe tubulointerstitial damage. Macrophages and T cells were present in equal proportion in the infiltrate at day 4. At day 14, the number of macrophages increased fivefold (2580/mm2), although T cells were unchanged (380/mm2). Proliferating macrophages (ED1+, BrdU+) increased from day 4 (4%) to day 14 (10%). M-CSF mRNA expression was strongly up-regulated in allografts compared with isografts and normal rat. In situ hybridization demonstrated M-CSF expression by resident and infiltrating cells. Renal tubular expression was minimally increased at day 4 but strongly up-regulated at day 14 (more than 50% of tubules positive), particularly in areas of tubular damage. Tubular M-CSF expression colocalized with areas of intense macrophage infiltration and proliferation. Serial sections with double labeling demonstrated that T cells were the dominant source of M-CSF at day 4, yet later in the rejection (day 14) the predominant sites of production were both renal tubular cells and interstitial macrophages. Renal production of M-CSF by graft-infiltrating (macrophages and T lymphocytes) and resident (tubular) cells was up-regulated during acute rejection. M-CSF promotes macrophage recruitment and proliferation and may thereby play a pathogenic role in acute rejection. The kinetics of M-CSF production during acute rejection suggest that local macrophage proliferation may be initiated by T cells and perpetuated by both renal tubular and autocrine release.

Combined Mycophenolate Mofetil and Losartan Therapy Arrests Established Injury in the Remnant Kidney

Previously it was shown that early treatment with mycophenolate mofetil (MMF) attenuated renal inflammation, glomerulosclerosis (GS), and interstitial expansion in the 5/6 ablation (NX) model. Angiotensin II antagonists also mitigate renal injury in NX, presumably by lowering glomerular pressure (P(GC)). This study investigated: (1) whether combined MMF/angiotensin II antagonists treatment affords superior protection compared with the respective monotherapies; and (2) whether this association is effective even when instituted late in the course of the disease. Adult male Munich-Wistar rats underwent NX, remaining untreated for 30 d. BP, albuminuria, and the extent of GS, interstitial expansion, and macrophage infiltration were then determined in 17 rats. The remaining 118 rats received either inert vehicle or one of the following: MMF, 10 mg/kg by gavage once daily; losartan potassium (L), 20 mg/dl in drinking water; or combined MMF/L treatment. Sixty days after ablation, untreated NX rats exhibited marked glomerular hypertension, which was attenuated by MMF and, more effectively, by either L or combined MMF/L treatment. At 120 d, hypertension and albuminuria were worsened in untreated NX rats, which exhibited intense macrophage infiltration and severe glomerular and interstitial disease. L and, to a lesser extent, MMF monotherapies attenuated these abnormalities, without preventing their progression. In rats given combined MMF/L therapy, macrophage infiltration, GS, and interstitial expansion remained at pretreatment levels. By acting on two distinct pathogenic mechanisms, combined MMF/L treatment arrested established renal injury in the NX model. Further investigation is needed to determine whether this association can prevent renal scarring in other models and in human disease.

Response of glia, mast cells and the blood brain barrier, in transgenic mice expressing interleukin-3 in astrocytes, an experimental model for CNS demyelination.

Transgenic mice overexpressing cytokines facilitate analysis of the effects of these immunomodulators on indigenous cells of the central nervous system. This study examines morphological aspects of demyelination and permeability changes, in a recently described transgenic model (termed GFAP-IL3). GFAP-IL3 mice develop progressive motor disease at approximately 5 months. Lesions identified after disease onset, showed activation of microglia, astroglial proliferation with phagocytosis of lipids, and immigration of macrophages and mast cells into neural parenchyma. Lymphocytes failed to appear until the later stages of the disease. Later, cerebellar and brain stem white matter contained focal demyelinating lesions with intense macrophage infiltration and a proliferative astrocytosis. Dystrophic axonal changes were noted, in addition to demyelination in heavily infiltrated lesions. Mast cells, variably present in the thalamus and meninges of wild type mice, were greatly increased at these sites in GFAP-IL3 mice. Blood-brain barrier (BBB) defects were documented with leakage of intravenously injected horseradish peroxidase. Mast cell infiltration into the CNS and their degranulation at the site of injury, may represent initial events in a spontaneous process of macrophage mediated demyelination in which glial cells and macrophages are both involved in the phagocytic process.