The severity of SARS-CoV-2 infection in K18-hACE2 mice is attenuated by a novel steroid-derivative in a gender-specific manner

BACKGROUND AND PURPOSE

COVID-19 infections caused by SARS-CoV-2 disseminated through human-to-human transmission can evoke severe inflammation. Treatments to reduce the SARS-CoV-2-associated inflammation are needed and are the focus of much research. In this study, we investigated the effect of N-ethyl-N'-[(3β,5α)-17-oxoandrostan-3-yl] urea (NEOU), a novel 17α-ketosteroid derivative, on the severity of COVID-19 infections.

EXPERIMENTAL APPROACH

Studies were conducted in SARS-CoV-2-infected K18-hACE2 mice.

KEY RESULTS

SARS-CoV-2-infected K18-hACE2 mice developed severe inflammatory crises and immune responses along with up-regulation of genes in associated signalling pathways in male more than female mice. Notably, SARS-CoV-2 infection down-regulated genes encoding drug metabolizing cytochrome P450 enzymes in male but not female mice. Treatment with NEOU (1 mg·kg-1 ·day-1 ) 24 or 72 h post-viral infection alleviated lung injury by decreasing expression of genes encoding inflammatory cytokines and chemokines while increasing expression of genes encoding immunoglobins. In situ hybridization using RNA scope™ probes and immunohistochemical assays revealed that NEOU increased resident CD169+ immunoregulatory macrophages and IBA-1 immunoreactive macrophage-dendritic cells within alveolar spaces in the lungs of infected mice. Consequentially, NEOU reduced morbidity more prominently in male than female mice. However, NEOU increased median survival time and accelerated recovery from infection by 6 days in both males and females.

CONCLUSIONS AND IMPLICATIONS

These findings demonstrate that SARS-CoV-2 exhibits gender bias by differentially regulating genes encoding inflammatory cytokines, immunogenic factors and drug-metabolizing enzymes, in male versus female mice. Most importantly, we identified a novel 17α-ketosteroid that reduces the severity of COVID-19 infection and could be beneficial for reducing impact of COVID-19.

STAT4 promotes critical neutrophil functions and is required for antimicrobial immunity in mice

Signal transducer and activator of transcription 4 (STAT4) is a transcription factor mainly associated with Th1 development, yet its role in neutrophil biology is unknown. We are the first to demonstrate that in vitro murine neutrophils stimulated with IL-12 directly activate STAT4 in a JAK2-dependent manner resulting in distinct transcriptional changes in antimicrobial response genes. STAT4-deficiency also impairs several neutrophil functions in vitro. Interestingly, IL-12 directly induces STAT4-dependent ROS formation at 14 hours, which is not due to cell death. Neutrophil extracellular trap (NET) formation in response to either LPS or heat-killed Pseudomonas aeruginosa results in decreased nuclear translocation of myeloperoxidase, decreased neutrophil elastase release, and decreased DNA release in STAT4-deficient neutrophils. In vivo neutrophil migration to the peritoneal cavity is blunted in Stat4−/− mice following either thioglycollate, CXCL1, or GM-CSF injections. Finally, we have generated Stat4floxLysMCre and Stat4floxS100A8Cre mice which are deficient in STAT4 in either myeloid cells or specifically neutrophils, respectively. Following in vivo infection with methicillin-resistant S. aureus, bacterial burden is increased in the blood and peritoneal cavity of Stat4floxLysMCre and Stat4floxS100A8Cre mice. Gene expression analysis of peritoneal exudate cells from infected mice show decreased expression of Ly6G/CD11b, further highlighting defective homing of Stat4−/− neutrophils in vivo. All together these data reveal an undiscovered role of STAT4 in neutrophil functions and a subsequent role of STAT4 in innate immunity and antimicrobial defense mechanisms.

Abnormalities in proinsulin processing in islets from individuals with longstanding T1D

We recently described the persistence of detectable serum proinsulin in a large majority of individuals with longstanding type 1 diabetes (T1D), including individuals with undetectable serum C-peptide. Here, we sought to further explore the mechanistic etiologies of persistent proinsulin secretion in T1D at the level of the islet, using tissues obtained from human donors. Immunostaining for proinsulin and insulin was performed on human pancreatic sections from the Network for Pancreatic Organ Donors with Diabetes (nPOD) collection (n = 24). Differential proinsulin processing enzyme expression was analyzed using mass spectrometry analysis of human islets isolated from pancreatic sections with laser capture microdissection (n = 6). Proinsulin processing enzyme mRNA levels were assessed using quantitative real-time PCR in isolated human islets (n = 10) treated with or without inflammatory cytokines. Compared to nondiabetic controls, immunostaining among a subset (4/9) of insulin positive T1D donor islets revealed increased numbers of cells with proinsulin-enriched, insulin-poor staining. T1D donor islets also exhibited increased proinsulin fluorescence intensity relative to insulin fluorescence intensity. Laser capture microdissection followed by mass spectrometry revealed reductions in the proinsulin processing enzymes prohormone convertase 1/3 (PC1/3) and carboxypeptidase E (CPE) in T1D donors. Twenty-four hour treatment of human islets with inflammatory cytokines reduced mRNA expression of the processing enzymes PC1/3, PC2, and CPE. Taken together, these data provide new mechanistic insight into altered proinsulin processing in long-duration T1D and suggest that reduced β cell prohormone processing is associated with proinflammatory cytokine-induced reductions in proinsulin processing enzyme expression.

The IL-12/STAT4 pathway associates with critical functions in neutrophils

Signal transducer and activator of transcription 4 (STAT4) becomes activated via phosphorylation by JAK/Tyk kinases in response to IL-12 and other cytokines, which results in downstream transcription of pro-inflammatory genes. Our preliminary data are the first to demonstrate that IL-12 induces phospho-STAT4 in neutrophils. STAT4, JAK2, and p38 MAPK, but not Tyk2, become rapidly phosphorylated in response to IL-12 treatment in a time dependent manner. Pharmacologic inhibition of JAK1/2, but not p38, resulted in a two-fold reduction in phospho-STAT4, confirming its role as a signalling intermediate during STAT4 activation. Although IL-12 does not induce ROS formation in the short term (<3 hours), we were surprised to discover a 4-fold increase in ROS production in response to long term IL-12 treatment (14 hrs), compared to only 1.5-fold increase in STAT4-deficient neutrophils. Additionally, we observed a dramatic 15-fold decrease in in vitro migration of STAT4-deficient neutrophils towards the chemoattractant GM-CSF compared to wild-type. Preliminary in vivo studies have revealed deficient migration to the peritoneal cavity of STAT4-deficient mice following intraperitoneal injection of GM-CSF. Finally, we demonstrate that in vitro NET formation in response to PMA treatment is impaired 5-fold in STAT4-deficient neutrophils compared to wild-type. These findings highlight the novel IL-12/STAT4 pro-inflammatory signalling pathway in murine neutrophils. Our data suggest a major contributory role of STAT4 in mediating neutrophil functions that have been previously associated with the progression of atherosclerosis. Future in vivo studies will determine the neutrophil-specific role of STAT4 in atherosclerotic mice.

Proinsulin Secretion Is a Persistent Feature of Type 1 Diabetes

OBJECTIVE

Abnormally elevated proinsulin secretion has been reported in type 2 and early type 1 diabetes when significant C-peptide is present. We questioned whether individuals with long-standing type 1 diabetes and low or absent C-peptide secretory capacity retained the ability to make proinsulin.

RESEARCH DESIGN AND METHODS

C-peptide and proinsulin were measured in fasting and stimulated sera from 319 subjects with long-standing type 1 diabetes (≥3 years) and 12 control subjects without diabetes. We considered three categories of stimulated C-peptide: 1) C-peptide positive, with high stimulated values ≥0.2 nmol/L; 2) C-peptide positive, with low stimulated values ≥0.017 but <0.2 nmol/L; and 3) C-peptide <0.017 nmol/L. Longitudinal samples were analyzed from C-peptide-positive subjects with diabetes after 1, 2, and 4 years.

RESULTS

Of individuals with long-standing type 1 diabetes, 95.9% had detectable serum proinsulin (>3.1 pmol/L), while 89.9% of participants with stimulated C-peptide values below the limit of detection (<0.017 nmol/L; n = 99) had measurable proinsulin. Proinsulin levels remained stable over 4 years of follow-up, while C-peptide decreased slowly during longitudinal analysis. Correlations between proinsulin with C-peptide and mixed-meal stimulation of proinsulin were found only in subjects with high stimulated C-peptide values (≥0.2 nmol/L). Specifically, increases in proinsulin with mixed-meal stimulation were present only in the group with high stimulated C-peptide values, with no increases observed among subjects with low or undetectable (<0.017 nmol/L) residual C-peptide.

CONCLUSIONS

In individuals with long-duration type 1 diabetes, the ability to secrete proinsulin persists, even in those with undetectable serum C-peptide.

Insulin resistance elicited in postpubertal primate offspring deprived of estrogen in utero

We recently demonstrated that offspring delivered to baboons deprived of estrogen during the second half of gestation exhibited insulin resistance prior to onset of puberty. Because gonadal hormones have a profound effect on insulin action and secretion in adults, we determined whether insulin resistance is retained after initiation of gonadal secretion of testosterone and estradiol. Glucose tolerance tests were performed in postpubertal baboon offspring of untreated and letrozole-treated animals (serum estradiol reduced >95 %). Basal fasting levels of insulin (P < 0.05) and peak 1 min and 1 + 3 + 5 min levels of glucose after glucose tolerance tests challenge (P < 0.03) were greater in offspring delivered to letrozole-treated, estrogen-deprived baboons than untreated animals. Moreover, the value for the HOMA-IR, an accepted index of insulin resistance, was 2-fold greater (P < 0.05) in offspring delivered to baboons treated with letrozole than in untreated animals. Collectively these results support the proposal that estrogen normally has an important role in programming mechanisms in utero within the developing fetus that lead to insulin sensitivity after birth.

Abstract 248: Stat4 Promotes Atherosclerosis by a Reduction in Cd8 + Tregs, Supporting Tfh and Plasma B Cell Development, T Cell Activation and Cd11b+ Cell Accumulation in the Aortic Wall

Atherosclerosis is an inflammatory disease of medium and large size arteries. Signal transducer and activator of transcription 4 (STAT4) is a transcription factor that supports generation of cells with features of both follicular helper T cells (Tfh) and T helper 1 (Th1) cells. To date, the role of STAT4 in atherogenesis and its effects on the induction of Tfh cells is an important area of active research. To investigate the role of STAT4 in atherogenesis, we generated STAT4-deficient, low-density lipoprotein-deficient ( Stat4 -/- Ldlr -/- ) mice. STAT4 deficiency resulted in a significant reduction in plaque burden within the aortas of Stat4 -/- Ldlr -/- mice fed a high fat/high carbohydrate diet with added cholesterol (DDC) for 16 weeks compared to age and diet-matched Ldlr -/- mice (p<0.01). STAT4 deficiency resulted in the reduction of CD19 + B cells (p<0.0001) CD8 + T cells (p<0.01) and CD3 + T cells (p<0.05) in spleens and peripheral lymph nodes of Stat4 -/- Ldlr -/ vs Ldlr -/ mice. Additionally, the number of splenic CXCR5 + Tfh cells and CD138 + plasma B cells was also diminished (p<0.003), suggesting reduced follicular germinal center activities under conditions of STAT4 deficiency. CD8 + Tregs are suppressors for autoreactive CD4 + T cells and also target Tfh cells. Importantly, CD8 + Tregs were elevated in spleens of Stat4 -/- Ldlr -/- compared to Ldlr -/- mice (p<0.05), suggesting that decreased Tfh cell numbers are due to increased CD8 + Tregs in Stat4 -/- Ldlr -/- mice. While STAT4 deficiency had no effects on M1/M2 macrophage polarization, Stat4-deficient M1 macrophages showed reduced MHCII expression and diminished secretion of pro-inflammatory cytokines upon stimulation in vitro. Furthermore, STAT4 deficiency led to a reduced MHCII expression by antigen-presenting cells (APC) and decreased content of CD11b + CD11c - cells in the aortas of Stat4 -/- Ldlr -/- vs Ldlr -/- mice. Together, these data demonstrate a pro-atherogenic role of STAT4 in multiple cell types via the regulation of CD8 + Treg-dependent germinal center formation, modulation of levels of APC activation, and alteration of the immune response within the aortic wall.

This work is supported by NHLBI HL112605 (J.N., E.G.), HL112605 supplemental grant 02S1 (J.N., P.T-M), and by HL107522 (E.G.).

Relative sensitivity of immunohistochemistry, multiple reaction monitoring mass spectrometry, in situ hybridization and PCR to detect Coxsackievirus B1 in A549 cells

BACKGROUND

Enteroviruses (EVs) have been linked to the pathogenesis of several diseases and there is a collective need to develop improved methods for the detection of these viruses in tissue samples.

OBJECTIVES

This study evaluates the relative sensitivity of immunohistochemistry (IHC), proteomics, in situ hybridization (ISH) and RT-PCR to detect one common EV, Coxsackievirus B1 (CVB1), in acutely infected human A549 cells in vitro.

STUDY DESIGN

A549 cells were infected with CVB1 and diluted with uninfected A549 cells to produce a limited dilution series in which the proportion of infected cells ranged from 10(-1) to 10(-8). Analyses were carried out by several laboratories using IHC with different anti-EV antibodies, ISH with both ViewRNA and RNAScope systems, liquid chromatography multiple reaction monitoring mass spectrometry (LC/MRM/MS/MS), and two modifications of RT-PCR.

RESULTS

RT-PCR was the most sensitive method for EV detection yielding positive signals in the most diluted sample (10(-8)). LC/MRM/MS/MS detected viral peptides at dilutions as high as 10(-7). The sensitivity of IHC depended on the antibody used, and the most sensitive antibody (Dako clone 5D8/1) detected virus proteins at a dilution of 10(-6), while ISH detected the virus at dilutions of 10(-4).

CONCLUSIONS

All methods were able to detect CVB1 in infected A549 cells. RT-PCR was most sensitive followed by LC/MRM/MS/MS and then IHC. The results from this in vitro survey suggest that all methods are suitable tools for EV detection but that their differential sensitivities need to be considered when interpreting the results from such studies.

STAT4 promotes atherosclerosis by supporting Tfh and plasma B cell development, T cell activation and CD11b+ cell accumulation in the aortic wall (LYM8P.632)

Atherosclerosis is an inflammatory disease of medium and large size arteries. Signal transducer and activator of transcription 4 (STAT4) is a transcription factor that supports the generation of cells with features of both follicular helper T cells (Tfh) and T helper 1 (Th1) cells. To date, the role of Stat-4 in atherosclerosis and the induction of Tfh cells in this disease has not been defined. To investigate the role of STAT4 in atherogenesis, we generated Stat-4-deficient low density lipoprotein-deficient (Stat4-/-Ldlr-/-) mice. Stat4 deficiency resulted in a significant reduction in atherosclerotic plaque burden within the aortas of Stat4-/-Ldlr-/- mice fed a high fat/high carbohydrate diet with added cholesterol (DDC) diet for 16 weeks compared to age and diet-matched Ldlr-/- control mice (p&lt;0.01). Next we examined spleens and peripheral lymph nodes (PLNs) of Stat4-/-Ldlr-/ mice and found decreased number of CD19+ B cells (p&lt;0.0001) and CD3+ T cells (p&lt;0.05). Interestingly, the number of Tfh cells and plasma B cells (p&lt;0.003) was also diminished in and spleens of Stat4-/-Ldlr-/- mice compared to Ldlr-/- mice. A significant reduction in CD11b+CD11c- cells and MHCII expression was detected in the aortas of Stat4-/-Ldlr-/- vs Ldlr-/- mice. Thus, the atherogenic effects of STAT4 are, at least partially, due to the modulation of the immune response via alterations of Tfh-dependent humoral response. Supported by R01 HL112605 and Suppl.Grant 02S1.

The role of a Stat4 deficiency in Atherosclerosis (CAM1P.237)

Atherosclerosis is a chronic inflammatory process that leads to plaque formation in large and medium size vessels. Th1 cells constitute a majority of plaque T cells and play a pro-atherogenic role. Signal transducer and activator of transcription 4 (Stat4) is a transcription factor involved in Th1 cell differentiation. To test a role of Stat4 in atherogenesis, we bred Stat4-deficient (Stat4-/-) and atherosclerosis-prone Apolipoprotein E (Apoe-/-) mice. Stat4 deficiency resulted in a 70% reduction in plaque burden in Stat4-/-Apoe-/- vs Apoe-/- mice (p&lt;0.01). Surprisingly, reduced atherogenesis was not due to attenuated IFNγ production suggesting an IFNγ-independent pro-atherogenic role of Stat4. Stat4 is highly expressed in T cells, but also detected in macrophages (MΦ). To further test an impact of Stat4 deficiency in myeloid cells, we analyzed activation status of MΦ. Stat4-/-Apoe-/- CD11b+ MΦ expressed low levels of CD69, MHCII, and CD86 when pulsed with LPS vs Apoe-/- MΦ. Differentiated in vitro Stat4-/-Apoe-/- M1 or M2 MΦ also had reduced expression of CCL2 and CXCL10 vs Apoe-/- M1 and M2 MΦ. Importantly, the percentage of aortic Ly6C+ (p&lt;0.02) and CD68+ (p&lt;0.06) cells was reduced in Stat4-/-Apoe-/- vs Apoe-/- mice. The data provides evidence for a functional role of Stat4 in atherosclerosis by elevating levels of MΦ activation and aortic MΦ content, and thus promoting the localized aortic pro-inflammatory immune response. Supported by R01 HL112605 and Suppl.Grant 02S1.

Abstract 452: Signal Transducer and Activator of Transcription 4 Deficiency Improves the Metabolic Phenotype and Skeletal Muscle Insulin Signaling in LDLr-/- Mice on Diabetogenic High-Cholesterol Diet

Insulin resistance and type2 diabetes are associated with increased incidence of cardiovascular disease. About 80% of the subjects with type2 diabetes die due to cardiovascular complications. We previously showed that STAT4 deficiency improves insulin resistance in C57Bl6 mice on high fat diet and STAT4-/-ApoE-/- mice develop significantly lower atherosclerosis compared to ApoE-/- controls. The goal of this project was to determine the effect of STAT4 deficiency in a combined model of atherosclerosis and insulin resistance. To this purpose we generated STAT4-/-LDLr-/- mice and fed them either a chow diet or a high carbohydrate (36.6%), high cholesterol (0.15%) (DDC) diet for 16 weeks (n=7-10). The LDLr-/- on DDC diet developed glucose intolerance and insulin resistance as well as atherosclerosis and hypercholesterolemia compared to chow fed controls. STAT4-/-LDLr-/- mice on DDC diet, although hypercholesterolemic had significantly reduced atherosclerotic plaques by en face staining (p<0.05). Also STAT4 deficient mice on DDC diet had significantly lower area under curve for both the insulin and glucose tolerance tests (p<0.01), as well as reduced fasted glucose (p<0.05) compared to LDLr-/- mice despite similar body weights. Glucose stimulated insulin secretion in isolated pancreatic islets was blunted in LDLr-/- mice on DDC compared to chow controls and STAT4 deficiency restored the insulin secretion in islets from DDC fed mice at levels comparable to chow controls. In vivo insulin challenge showed reduced activation of IR, IRS-1 and Akt in LDLr-/- mice on DDC compared to chow controls in adipose tissue and skeletal muscle. STAT4-/-LDLr-/- on DDC diet had significantly improved activation of IRS-1 and Akt in skeletal muscle but not in adipose tissue. IR activation was constitutively higher in in STAT4-/-LDLr-/- mice on DDC compared to chow and did not change after insulin stimulation suggesting that STAT4 deficiency restores insulin signaling via a post-receptor mechanism. In conclusion, STAT4 deficiency reduces insulin resistance and improves glucose intolerance primarily by improving insulin signaling in skeletal muscle and by increasing islet insulin secretion. This may explain in part the athero-protective phenotype in STAT4-/-LDLr mice.

Association of proinflammatory cytokines and islet resident leucocytes with islet dysfunction in type 2 diabetes

AIMS/HYPOTHESIS

Chronic inflammation in type 2 diabetes is proposed to affect islets as well as insulin target organs. However, the nature of islet inflammation and its effects on islet function in type 2 diabetes remain unclear. Moreover, the immune cell profiles of human islets in healthy and type 2 diabetic conditions are undefined. We aimed to investigate the correlation between proinflammatory cytokine expression, islet leucocyte composition and insulin secretion in type 2 diabetic human islets.

METHODS

Human islets from organ donors with or without type 2 diabetes were studied. First and second phases of glucose-stimulated insulin secretion were determined by perifusion. The expression of inflammatory markers was obtained by quantitative PCR. Immune cells within human islets were analysed by FACS.

RESULTS

Type 2 diabetic islets, especially those without first-phase insulin secretion, displayed higher CCL2 and TNFa expression than healthy islets. CD45(+) leucocytes were elevated in type 2 diabetic islets, to a greater extent in moderately functional type 2 diabetic islets compared with poorly functional ones, and corresponded with elevated ALOX12 but not with CCL2 or TNFa expression. T and B lymphocytes and CD11c(+) cells were detectable within both non-diabetic and type 2 diabetic islet leucocytes. Importantly, the proportion of B cells was significantly elevated within type 2 diabetic islets.

CONCLUSIONS/INTERPRETATION

Elevated total islet leucocyte content and proinflammatory mediators correlated with islet dysfunction, suggesting that heterogeneous insulitis occurs during the development of islet dysfunction in type 2 diabetes. In addition, the altered B cell content highlights a potential role for the adaptive immune response in islet dysfunction.

Abstract 152: Stat4 Deficiency limits the Development and Progression of Atherosclerosis

T helper 1 (Th1) cells constitute the majority of plaque infiltrating IFNγ+ T cells and play a pro-atherogenic role. Th1 cells are induced via IFNγ-dependent activation of T-box expressed in T cells (Tbet) and/or IL-12-dependent activation of signal transducer and activator of transcription 4 (Stat4). While the role of Tbet in atherosclerosis is established, the impact of the IL-12/Stat4-dependent pathway is not well defined. To address the role of Stat4 in atherosclerosis, we bred Stat4-deficient mice with Apolipoprotein E-deficient mice to generate Stat4-/-Apoe-/- mice. Deficiency of Stat4 resulted in approximately a 70% reduction in the plaque burden for 34 week old Stat4-/-Apoe-/- mice fed a chow diet and in 12 week old Stat4-/-Apoe-/- mice fed a western diet there was approximately a 40% reduction in plaque burden, both compared with diet matched Apoe-/- controls females (p<0.001). To assess the effect of Stat4 on Th1 and Treg cell differentiation, we performed an in vitro polarization assay. Deficiency of Stat4 reduced differentiation of IFNγ+ Th1 cells in Th1 conditions, but supported the induction of Tregs in Treg polarizing conditions, confirming the importance of Stat4 in regulating the Th1/Treg balance. In contrast to the in vitro results, we found no difference in the expression of both IFNγ and Foxp3 amongst Stat4-/-Apoe-/- and Apoe-/- lymph nodes and splenic CD4+ T cells; suggesting that additional cytokines in vivo may induce IFNγ+Th1 and inhibit Treg differentiation. Stat4 deficiency also resulted in increased splenic B cell numbers and a slight increase in B1a dependent T15/E06 mRNA expression. Stat4 is a powerful regulator of chemokine expression within peripheral tissues. Adoptively transferred Apoe-/- B cells and CD11b+ cells migrated more efficiently into Stat4-/-Apoe-/- aortas compared to Apoe-/- recipients. However, percentages of macrophages, as determined by CD11b+CD68+ were reduced within the spleens and aortas of Stat4-/-Apoe-/- mice as compared to Apoe-/- controls at steady state conditions. In conclusion, Stat4 deficiency results in reduced atherosclerosis via the modulation of B cell function and aortic leukocyte content.

Genistein induces pancreatic beta-cell proliferation through activation of multiple signaling pathways and prevents insulin-deficient diabetes in mice

Genistein, a flavonoid in legumes and some herbal medicines, has various biological actions. However, studies on whether genistein has an effect on pancreatic beta-cell function are very limited. In the present study, we investigated the effect of genistein on beta-cell proliferation and cellular signaling related to this effect and further determined its antidiabetic potential in insulin-deficient diabetic mice. Genistein induced both INS1 and human islet beta-cell proliferation after 24 h of incubation, with 5 mum genistein inducing a maximal 27% increase. The effect of genistein on beta-cell proliferation was neither dependent on estrogen receptors nor shared by 17beta-estradiol or a host of structurally related flavonoid compounds. Pharmacological or molecular intervention of protein kinase A (PKA) or ERK1/2 completely abolished genistein-stimulated beta-cell proliferation, suggesting that both molecules are essential for genistein action. Consistent with its effect on cell proliferation, genistein induced cAMP/PKA signaling and subsequent phosphorylation of ERK1/2 in both INS1 cells and human islets. Furthermore, genistein induced protein expression of cyclin D1, a major cell-cycle regulator essential for beta-cell growth. Dietary intake of genistein significantly improved hyperglycemia, glucose tolerance, and blood insulin levels in streptozotocin-induced diabetic mice, concomitant with improved islet beta-cell proliferation, survival, and mass. These results demonstrate that genistein may be a natural antidiabetic agent by directly modulating pancreatic beta-cell function via activation of the cAMP/PKA-dependent ERK1/2 signaling pathway.

Altered autoimmune response in NOD-Alox15null mice (99.13)

12/15-lipoxygenase (12/15-LO) reacts with fatty acids to produce pro-inflammatory lipids, enhance IL-12 production by macrophages (MΦ), and its product 12-(S)-HETE induces pancreatic β-cell apoptosis at nM concentrations. Congenic NOD mice deficient in 12/15-LO (NOD-Alox15null) show a significant decrease in Type 1 diabetes (T1D) development (2.5 vs. &gt;60% in ♀ by 30 wks). We tested the effects of the deficiency on the immune system in NOD-Alox15null vs. NOD mice. Adoptive transfer of diabetic (diab) or non-diabetic (non-diab) NOD, and non-diab NOD-Alox15null splenocytes (cells) determined ability of T1D disease transfer in NOD.scids. Both diab and non-diab NOD cells conferred T1D in NOD.scid hosts, but non-diab NOD-Alox15null cells did not (&gt;8 wks post-transfer). NOD-Alox15null.scids were also injected with either NOD (diab and non-diab) or NOD-Alox15null (non-diab) cells. NOD cells still transferred disease, but NOD-Alox15null cells did not. As transferred splenocytes were mainly T and B cells, we tested for 12/15-LO mRNA expression in these subsets. 12/15-LO levels were minimally detectable, suggesting that immune effects are likely due to indirect effects on B and T cells. To study the mechanism, we looked at the role of 12/15-LO on APCs. Fewer MΦ infiltrate the pancreas of NOD-Alox15null mice at 4 wks of age compared to NOD controls. Also, MΦ from 10-wko NOD-Alox15null mice show reduced IL-12 expression compared to age-matched NODs. Therefore, 12/15-LO is a key regulator of the autoimmune response leading to T1D.

Upregulation of aldose reductase during foam cell formation as possible link among diabetes, hyperlipidemia, and atherosclerosis

OBJECTIVE

Aldose reductase (AR) is the rate-limiting enzyme of the polyol pathway. In diabetes, it is related to microvascular complications. We discovered AR expression in foam cells by gene chip screening and hypothesized that it may be relevant in atherosclerosis.

METHODS AND RESULTS

AR gene expression and activity were found to be increased in human blood monocyte-derived macrophages during foam cell formation induced by oxidized LDL (oxLDL, 100 microg/mL). AR activity as photometrically determined by NADPH consumption was effectively inhibited by the AR inhibitor epalrestat. oxLDL-dependent AR upregulation was further increased under hyperglycemic conditions (30 mmol/L D-glucose) as compared to osmotic control, suggesting a synergistic effect of hyperlipidemia and hyperglycemia. AR was also upregulated by 4-hydroxynonenal, a constituent of oxLDL. Upregulation was blocked by an antibody to CD36. AR inhibition resulted in reduction of oxLDL-induced intracellular oxidative stress as determined by 2'7'-dichlorofluoresceine diacetate (H2DCFDA) fluorescence, indicating that proinflammatory effects of oxLDL are partly mediated by AR. Immunohistochemistry showed AR expression in CD68+ human atherosclerotic plaque macrophages.

CONCLUSIONS

These data show that oxLDL-induced upregulation of AR in human macrophages is proinflammatory in foam cells and may represent a potential link among hyperlipidemia, atherosclerosis, and diabetes mellitus.

Rosiglitazone Reduces the Accelerated Neointima Formation After Arterial Injury in a Mouse Injury Model of Type 2 Diabetes

Background— Hyperglycemia (HG) and hyperinsulinemia (HI) may be factors enhancing the atherosclerotic complications of diabetes. We hypothesized that specific feeding of C57BL/6 apolipoprotein (apo) E −/− mice would alter their metabolic profiles and result in different degrees of neointima (NI) formation. We additionally hypothesized that an insulin-sensitizing agent (rosiglitazone) would prevent the development of type 2 diabetes and reduce neointima formation after carotid wire injury measured at 28 days.

Methods and Results— Fasting glucose and insulin levels were elevated in the Western diet (WD) group, with a trend toward higher insulin levels and euglycemia in the fructose diet (FD)–fed mice. NI formation was exaggerated in the WD group compared with the FD or chow control groups. In the WD mice given rosiglitazone, glucose and insulin levels remained normal and NI formation was significantly reduced, as was NI macrophage content.

Conclusions— These findings demonstrate that apoE −/− mice fed a WD develop type 2 diabetes with an exaggerated NI response to injury. FD mice maintain euglycemia but develop insulin resistance, with an intermediate degree of NI growth compared with chow diet controls. Rosiglitazone prevents the development of hyperglycemia and hyperinsulinemia and normalizes the insulin release profile in the apoE −/− , WD-fed mouse and significantly reduces NI formation by 65% after carotid wire injury while reducing macrophage infiltration. These data support the hypothesis that type 2 diabetes in the setting of elevated cholesterol accelerates the response to vascular injury and suggest that agents that improve insulin sensitivity may have therapeutic value in reducing restenosis in type 2 diabetes.

Overexpression of 12-lipoxygenase and cardiac fibroblast hypertrophy

Leukocyte-type 12-lipoxygenase (12-LO) catalyzes the conversion of arachidonic acid (C20:4) to 12-hydroperoxyeicosatetraenoic acid, which in turn reduces to 12-hydroxyeicosatetraenoic acid (12-HETE) by glutathione peroxidase. Results of studies in vascular smooth muscle and in adrenal glomerulosa cells have supported the concept that 12-LO is an important mediator of angiotensin II (Ang II) action. Studies also indicate that 12-HETE is a potent growth-promoting factor and facilitates proliferation in Chinese hamster ovary (CHO) fibroblast cells overexpressing the Ang II AT1a receptor (CHO-AT1a cells). However, until recently, the role of 12-LO in cardiac cells had not been explored. Cardiac fibroblasts are a major source of matrix proteins, which can lead directly to extracellular matrix deposition and cardiac fibrosis. To elucidate the role of the 12-LO pathway in fibroblast cell growth, 12-LO cDNA was stably transfected into fetal rat cardiac fibroblasts. The cells overexpressing 12-LO showed an increase in cell protein content and enlargement in cell size with a slowing of cell division rate. Furthermore, the cells overexpressing 12-LO showed increases in fibronectin and collagen deposition compared with mock-transfected cells. These features are most consistent with cellular hypertrophy instead of proliferation. It is proposed that cardiac fibroblast cells overexpressing 12-LO retain the characteristics of fibroblasts, but with additional features of myocytes that have the function of showing cell hypertrophy. These results provide the basis for proposing the hypothesis that enhanced 12-LO expression or activity could play a role in pathogenic cardiac enlargement.

In-situ measurement of ammonium and nitrate in the activated sludge process

A new in-situ probe is presented for the continuous measurement of ammonium and nitrate in wastewater. It requires no sample preparation and is installed directly in the process liquid. This new low-cost probe significantly reduces investment and operating costs and requires minimum maintenance. The paper describes the sensor principle and test results from three different probe locations: the primary clarifier effluent, the activated sludge tank and the nitrifying biofilter influent. Reference measurements were carried out by means of conventional analyzers with ultrafiltration, an in-situ UV spectrometer for the nitrate and laboratory analysis of spot and 2h-composite samples. The aim of the study was to investigate the operational reliability and accuracy of the new probe and the expenditure required for its maintenance and calibration. The tests showed that the new probe performed very well overall and required minimum maintenance. Some problems were observed during the biofilter plant test. They are assumed to be related to substantial changes in the wastewater composition.

Effects of allogeneic bone marrow transplantation on recipient bone mineral density: A prospective study

Allogeneic bone marrow transplant (BMT) recipients have many known risk factors for developing decreased bone mineral density (BMD) after transplantation. We performed a prospective sequential evaluation of BMD in the lumbar spine and nondominant hip using dual-energy x-ray absorptiometry (DEXA) in a cohort of 47 adult patients (median age, 43 years) who were undergoing radiation-based BMT for hematologic malignancies. Baseline DEXA studies were performed before BMT and repeated at 3 to 4 months, 6 to 8 months, and 12 to 14 months after BMT. The majority of patients (60%) had been minimally treated with combination cytotoxic chemotherapy, having received no more than 1 treatment regimen before BMT. Graft-versus-host disease prophylaxis consisted of cyclosporine in combination with either methotrexate or prednisone, or both. Mean lumbar spine and hip BMD were normal before BMT (spine: 1.01 g/cm2, z score = 96%; hip: 0.86 g/cm2, z score = 100%) and gradually decreased (spine: 0.98 g/cm2, z score = 94%; hip: 0.76 g/cm2, z score = 91%) at 12 to 14 months. These declines were statistically significant (P < .006 and < .002 for lumbar spine; P < .001 and < .001 for hip). In addition, the sharpest decline occurred during the first 6 months after BMT and was more marked in the hip than the lumbar spine. These data suggest that BMT adversely affects BMD in this patient population.

Women and HIV: when to test?

The devastating effects of HIV infection in women can be altered dramatically with new therapies. Certain clinical syndromes, including oral thrush, diffuse lymphadenopathy, wasting, unexplained fevers, or oral hairy leukoplakia, clearly indicate a need for HIV testing. This article reviews other clinical syndromes, both gender-specific and non-gender-specific, that may prompt the practitioner to consider HIV testing.

Evidence for 12-lipoxygenase induction in the vessel wall following balloon injury

OBJECTIVE

Vascular smooth muscle cell (VSMC) migration and proliferation are key events in the development of atherosclerosis and restenosis following angioplasty. These events are mediated by several growth factors and cytokines whose cellular effects include activation of phospholipases and arachidonic acid metabolism via the lipoxygenase (LO) pathway. Since 12-LO products have potent growth and chemotactic effects, we have examined if 12-LO is upregulated in the neointima of injured rat carotid arteries and also if LO inhibition could attenuate neointimal thickening.

METHODS

The left common carotid arteries of male Sprague Dawley rats were injured using a 1.8 F PTCA balloon catheter. Four-fourteen days after injury, injured and uninjured tissue samples were processed for histology, and immunohistochemistry or polymerase chain reaction (PCR) to examine 12-LO expression.

RESULTS

Twelve days after injury, immunohistochemical staining with a 12-LO antibody revealed intense staining in injured left carotid arteries, mainly in neointimal VSMCs and inflammatory cells, but not in the uninjured right arteries. There was also a marked upregulation of 12-LO mRNA (over five-fold by competitive PCR) in the injured arteries. Treatment of the arteries with a LO inhibitor, phenidone, soon after injury resulted in significant inhibition of neointimal thickening. In contrast, a cyclooxygenase inhibitor, ibuprofen, had no effect.

CONCLUSIONS

These results indicate for the first time that balloon injury results in marked induction of 12-LO mRNA and protein expression in the vessel wall. Furthermore, LO pathway activation may mediate, at least in part, the development of the lesion or plaque instability, suggesting a novel target for therapeutic intervention to block these pathological events.

Angiotensin II signaling in vascular smooth muscle cells under high glucose conditions

The mechanisms responsible for the accelerated cardiovascular disease in diabetes, as well as the increased hypertrophic effects of angiotensin II (Ang II) under hyperglycemic conditions, are not very clear. We examined whether the culture of vascular smooth muscle cells (VSMC) under hyperglycemic conditions to simulate the diabetic state can lead to increased activation of key growth- and stress-related kinases, such as the mitogen-activated protein kinases (MAPKs), in the basal state and in response to Ang II. Treatment of porcine VSMC for short time periods (0.5 to 3 hours) with high glucose (HG; 25 mmol/L) markedly increased the activation of the extracellular signal-regulated kinase (ERK1/2) and c-Jun/N-terminal kinase (JNK) relative to cells cultured in normal glucose (NG; 5.5 mmol/L). p38 MAPK also was activated by HG, and this effect remained sustained for several hours. Ang II treatment increased the activity of all 3 families of MAPKs. Ang II-induced ERK activation was potentiated nearly 2-fold in cells treated with HG for 0.5 hour. However, Ang II-induced JNK was not altered. In VSMC cultured for 24 hours with HG, Ang II and HG displayed an additive response on p38 MAPK activity. MAPKs can lead to activation of transcription factors such as activator protein-1 (AP-1). HG alone significantly increased AP-1 DNA-binding activity. Furthermore, Ang II and HG combined had additive effects on AP-1 activity. These results suggest that increased activation of specific MAPKs and downstream transcription factors, such as AP-1, may be key mechanisms for the increased VSMC growth potential of HG alone and of Ang II under HG conditions.

Insulin potentiates platelet-derived growth factor action in vascular smooth muscle cells

Correlative studies have indicated that hyperinsulinemia is present in many individuals with atherosclerosis. Insulin resistance has also been linked to cardiovascular disease. It has proved to be difficult to decipher whether hyperinsulinemia or insulin resistance plays the most important role in the pathogenesis of atherosclerosis and coronary artery disease. In this study, we demonstrate that insulin increases the amount of farnesylated p21Ras in vascular smooth muscle cells (VSMC), thereby augmenting the pool of cellular Ras available for activation by platelet-derived growth factor (PDGF). In VSMC incubated with insulin for 24 h, PDGF's influence on GTP-loading of Ras was significantly increased. Furthermore, in cells preincubated with insulin, PDGF increased thymidine incorporation by 96% as compared with a 44% increase in control cells (a 2-fold increment). Similarly, preincubation of VSMC with insulin increased the ability of PDGF to stimulate gene expression of vascular endothelial growth factor 5- to 8-fold. The potentiating influence of insulin on PDGF action was abrogated in the presence of a farnesyltransferase inhibitor. Thus, the detrimental influence of hyperinsulinemia on the arterial wall may be related to the ability of insulin to augment farnesyltransferase activity and provide greater amounts of farnesylated p21Ras for stimulation by various growth promoting agents.

Quantitative and qualitative performance of stroke versus normal elderly on six clock drawing systems

The utility of the Clock Drawing Test (CDT) in localizing lesions has not been thoroughly examined to date. In the present study, six scoring systems (Freedman et al., 1994; Ishiai, Sugishita, Ichikawa, Gono, & Watabiki, 1993; Mendez, Ala, & Underwood, 1992; Rouleau, Salmon, Butters, Kennedy, & McGuife, 1992; Sunderland et al., 1989; Tuokko, Hadjistavropoulos, Miller, & Beattie, 1992; Watson, Arfken, & Birge, 1993; Wolf-Klein, Silverstone, Levy, & Brod, 1989) were used to assess clock drawings by 76 stroke patients and 71 normal controls. Significant differences were found between normals and stroke patients on all scoring systems for both quantitative and qualitative features of the CDT. Quantitative indices were not helpful in differentiating between various stroke groups (left versus right versus bilateral stroke; cortical versus subcortical stroke; anterior versus posterior stroke). Qualitative features were helpful in lateralizing lesion site and differentiating subcortical from cortical groups. Correlational analyses revealed that CDT performance was related to visuospatial processing and measures commonly used in cognitive screening.

Role of lipoxygenases in breast cancer

The interaction of growth factors such as epidermal growth factor (EGF) with their receptors on breast cancer cells can lead to the hydrolysis of phospholipids and release of fatty acids such as arachidonic acid which can be further metabolized by the lipoxygenase (LO) pathway. Several LO products have been shown to stimulate oncogenes and have mitogenic and chemotactic effects. The 12-LO product, 12-hydroxyeicosatetraenoic acid (12(S)HETE), has been shown to play a key role in mediating several steps of the process of hematogenous metastasis and tumor cell adhesion. 12-LO can also be activated by several growth factors and inflammatory cytokines. A growing body of evidence suggests that specific metabolites of arachidonic and/or linoleic acid serve as central elements in signal pathways necessary for cell mitogenesis as induced by growth factors or oncogenic transformation. This review examines the role of LOs in breast cancer. The growth of breast cancer cells has been shown to increased by certain LO products and, LO pathway inhibitors could block the growth of some breast cancer cells. 12-LO activity and expression was increased in breast cancer tissues relative to the uninvolved normal tissue, and also in cultured breast cancer cells relative to normal breast cells. Treatment of the breast cancer cell line, MCF-7 cells, with epidermal growth factor (EGF), led to significant increases in 12-LO activity and expression. Thus, activation of the 12-LO pathway may play a key role in basal and EGF-induced breast cancer cell growth.

Effects of high glucose on vascular endothelial growth factor expression in vascular smooth muscle cells

Vascular endothelial growth factor (VEGF), in addition oto its growth-promoting effects on endothelial cells, can also increase vascular permeability and monocyte migration. It has therefore been implicated in the pathogenic neovascularization associated with diabetic retinopathy and atherosclerosis. However, the factors regulating VEGF expression in the vascular wall are not fully understood. In this study, we examined the regulation of VEGF expression in vascular smooth muscle cells (VSMC) by hyperglycemia as well as by angiotensin II (ANG II). We also examined whether the 12-lipoxygenase (12-LO) product 12-hydroxyeicosatetraenoic acid (12-HETE) can alter VEGF expression, since 12-LO products of arachidonic acid have angiogenic properties, and ANG II as well as high glucose (HG, 25 mM) can increase 12-LO activity and expression in VSMC. Studies were carried out in human (HSMC) or porcine VSMC (PSMC), which were cultured for at least two passages under normal glucose (NG, 5.5 mM) or HG conditions. HG culture alone increased the expression of VEGF mRNA and protein in both HSMC and PSMC. Furthermore, ANG II treatment significantly induced VEGF mRNA and protein expression only in VSMC cultured in HG and not NG. In addition, 12-HETE significantly increased VEGF mRNA and protein expression in HSMC cultured in NG as well as in HG. Cells cultured in HG also secreted significantly greater amounts of VEGF into the culture medium. These results suggest that elevated VEGF production under HG conditions may play a role in the accelerated vascular disease observed in diabetes.

Use of a hammerhead ribozyme with cationic liposomes to reduce leukocyte type 12-lipoxygenase expression in vascular smooth muscle

Chemically synthesized hammerhead-type ribozymes targeted against the porcine leukocyte-type 12-lipoxygenase (LO) have been developed and studied. One chimeric ribozyme consists of DNA in the non-enzymatic portions, and RNA in the enzymatic core as well as two phosphorothioate internucleotide linkages at 3' terminus. The second ribozyme consists of ribonucleotide sequences generated by in vitro transcription. In this chapter we describe methodologies to first analyze the ribozyme catalytic activity in vitro by studying cleavage of target RNA in vitro. The subsequent sections will describe how to target the catalytic ribozyme and deliver it to porcine vascular smooth muscle cells (PVSMC) by a liposome-mediated method. Finally ways to evaluate its activity to inhibit expression of the 12-LO mRNA will be presented. These results demonstrate the feasibility of using ribozymes as novel candidates for therapeutic agents to block specific gene expression in vascular cells.

The Mattis Dementia Rating Scale in nursing home octogenarians and nonagenarians: effects of age and education

Despite their increasing representation in the population, little is known about the neuropsychological test performance of the oldest old, particularly those who live in residential settings. Limited published data and clinical experience suggest that this group is more likely to perform in the impaired range on standardized tests when cut-offs developed with younger groups are used. We examined the Dementia Rating Scale (DRS) performance of 82 nondemented nursing home residents, aged 80 to 99, with a mean education level of 11 years. Using published norms and cutoffs, a large percentage of this sample performed in the impaired range, particularly on the initiation and conceptualization subtests and on the total score. Education, but not age, was significantly related to performance in this sample. Percentages of patients misclassified were substantial in all groups, but were higher in those with less than 13 years of education. Using a lower total-score cutoff of 110 reduced the percentage of misclassifications markedly. We recommend the development and use of revised cutoff scores for the evaluation of very elderly nursing home residents.

Increased 12-lipoxygenase expression in breast cancer tissues and cells. Regulation by epidermal growth factor

The interaction of growth factors, such as epidermal growth factor (EGF) with their receptors, on breast cancer cells can lead to the hydrolysis of phospholipids and release of fatty acids, such as arachidonic acid, which can be further metabolized by the lipoxygenase (LO) pathway. Several LO products have been shown to stimulate oncogenes and have mitogenic and chemotactic effects. In this study, we have evaluated the regulation of 12-LO activity and expression in breast cancer cells and tissues. Leukocyte-type 12-LO messenger RNA (mRNA) expression was studied by a specific RT-PCR method in matched, normal, uninvolved and cancer-involved breast tissue RNA samples from six patients. In each of these six patients, the cancer-involved section showed a much higher level of 12-LO mRNA than the corresponding normal section. 12-LO mRNA levels also were greater in two breast cancer cell lines, MCF-7 and COH-BR1, compared with the nontumorigenic breast epithelial cell line, MCF-10F. The growth of the MCF-7 cells was significantly inhibited by two specific LO blockers but not by a cyclooxygenase blocker. Treatment of serum-starved MCF-7 cells with EGF for 4 h led to a dose-dependent increase in the formation of the 12-LO product, 12-hydroxyeicosatetraenoic acid. EGF treatment also increased the levels of the leukocyte-type 12-LO protein expression at 24 h. These results suggest that activation of the 12-LO pathway may play a key role in basal and EGF-induced breast cancer cell growth.

The role of nitric oxide in the regulation of aldosterone synthesis by adrenal glomerulosa cells

The role of nitric oxide (NO) in the regulation of aldosterone synthesis in the adrenal glomerulosa is not known. In this study, we observed that liberators of NO such as S-nitroso-N-acetyl-penicillamine (SNAP), sodium nitroprusside (Snp) and spermine nonoate (SNO) could significantly inhibit angiotensin II (AII) and ACTH-induced aldosterone synthesis in isolated rat and cultured human adrenal glomerulosa cells. To evaluate more precisely whether glomerulosa cells express NO synthase, we performed immunoblotting experiments with antibodies specific for the endothelial type ecNO synthase as well as the neuronal NO synthase. This revealed the presence of the ecNO synthase in rat adrenal capsules, in normal and in adenomatous human adrenal glomerulosa tissue, as well as in freshly dispersed rat adrenal glomerulosa cells. Furthermore, on immunohistochemical analysis, rat adrenal glomerulosa cell sections showed strongly positive staining for ecNO synthase. These results suggest that NO may be an important negative modulator of adrenal glomerulosa steroidogenesis.

Formation of an F2-isoprostane in vascular smooth muscle cells by elevated glucose and growth factors

Recently a series of non-cyclooxygenase-derived prostanoids were identified in vivo in humans and in animal models of free radical injury as products of free radical-catalyzed peroxidation of arachidonic acid. One of these, an F2-isoprostane, 8-epiprostaglandin F2 alpha (8-epi-PGF 2 alpha), is a potent renal vasoconstrictor and can increase vascular smooth muscle cell (VSMC) DNA synthesis. In the present study we have evaluated whether F2-isoprostanes play a role in diabetic vascular dysfunction by studying the formation of 8-epi-PGF2 alpha in porcine VSMC (PVSMC) cultured under hyperglycemic conditions. 8-Epi-PGF2 alpha levels were quantitated by a specific enzyme immunoassay. We also examined whether certain VSMC growth factors, such as angiotensin II, platelet-derived growth factor, and transforming growth factor-beta, could also regulate the formation of 8-epi-PGF2 alpha. We observed that PVSMC cultured under high glucose (HG) conditions produced significantly higher amounts of 8-epi-PGF2 alpha compared with normal glucose (NG) conditions (3.7 +/- 0.13 ng/10(6) cells in HG vs. 2.9 +/- 0.2 ng/10(6) cells in NG, P < 0.05). Furthermore, all three growth factors tested evoked significant dose-dependent formation of 8-epi-PGF2 alpha (ranging from 125 to 220% of control). These results suggest that 8-epi-PGF2 alpha formation, as a result of hyperglycemia or due to growth factor action, may lead to increased VSMC growth and contribute to the complications of diabetes and cardiovascular disease.

A 12-lipoxygenase product, 12-hydroxyeicosatetraenoic acid, is increased in diabetics with incipient and early renal disease

Earlier studies in diabetic animal models or ex vivo from diabetics suggest a deficiency in prostacyclin (PGI2) production and an increase in an alternate arachidonic acid metabolite, 12-hydroxyeicosatetraenoic acid (12-HETE), which stimulates angiogenesis, mitogenesis, and inhibits renin secretion. We studied the urinary excretion rate of 6-keto-PGF1 alpha (a stable metabolite of PGI2) and 12-HETE in controls and 42 noninsulin-dependent diabetes mellitus (NIDDM) patients with normal renal function and those with micro- or macroalbuminuria/hyporeninemic hypoaldosteronism (HH). The 2 eicosanoids were measured in urine using previously described high pressure liquid chromatography and RIA methods. Normal subjects and patients with NIDDM and microalbuminuria were infused with low dose calcium infusions that stimulate prostacyclin production in normal subjects. The PGI2 excretion rate of NIDDM patients with normal renal function was not different from that of controls (143 +/- 17 vs. 118 +/- 34 ng/g creatinine), but was reduced in those with microalbuminuria (75 +/- 10) and in macroalbuminuria patients (48 +/- 7; P < 0.01). In contrast, 12-HETE was increased in diabetics with normal renal function as well as in those with micro- or macroalbuminuria patients (69 +/- 18 vs. 250 +/- 62 vs. 226 +/- 60 and 404 +/- 131 ng/g creatinine; P < 0.01). Calcium did not stimulate PGI2, but increased 12-HETE in diabetics with microalbuminuria in contrast to levels in normal subjects. HH patients excreted less PGI2 (as previously reported), but had increased 12-HETE. HETE/PGI2 ratios further demonstrated these changes in the various groups. In a nondiabetic hypertensive microalbuminuria group, 12-HETE excretion was normal (73 +/- 28 ng/g creatinine). We conclude that the lipoxygenase product 12-HETE is increased early in the diabetic process, whereas PGI2 production is progressively impaired in NIDDM. These changes may play a role in the vascular disease of diabetes and partially explain the HH syndrome.

Ribozyme-mediated inhibition of expression of leukocyte-type 12-lipoxygenase in porcine aortic vascular smooth muscle cells

Activation of a leukocyte-type 12-lipoxygenase (12-LO) has been proposed to be an important mechanism for angiotensin II- and glucose-induced vascular smooth muscle cell growth. Currently, no specific pharmacological inhibitors for the leukocyte-type 12-LO are available to test this hypothesis. We have therefore designed a chimeric DNA-RNA hammerhead ribozyme to produce cleavage at the first GUC sequence at nucleotide 7 of porcine leukocyte 12-LO mRNA. The ribozyme was tested in vitro with a 206-base 12-LO mRNA as substrate. We observed that the ribozyme specifically and dose-dependently cleaved porcine leukocyte 12-LO mRNA at the predicted site under physiological temperature. Furthermore, we also efficiently delivered the ribozyme into porcine aortic vascular smooth muscle cells by transfection with cationic liposomes. The ribozyme caused a dose-dependent decrease in levels of porcine leukocyte-type 12-LO mRNA in these cells and was more potent than an antisense oligonucleotide directed against porcine leukocyte 12-LO. The 12-LO ribozyme also attenuated 12-LO protein levels in the cells. The action of the ribozyme was primarily a result of its catalytic activity, since a modified ribozyme that lacks catalytic activity showed reduced effects. This represents the first ribozyme directed against a mammalian LO pathway. These results demonstrate the potential utility of new ribozyme technology to generate novel agents for gene modulation experiments to modify the development or progression of vascular disease in humans.

Renin response to 12-hydroxyeicosatetraenoic acid is increased in diabetic rats

Eicosanoids (prostaglandins) can alter renin secretion and angiotensin (ANG) II action. We have studied the effects of both prostacyclin and a lipoxygenase (LO) product, 12-hydroxyeicosatetraenoic acid (12-HETE), on renin in normal and streptozotocin-induced diabetic rats. 12-HETE is not only a potent inhibitor of basal renin secretion but also a key mediator of ANG II-induced renin inhibition. We have also examined the effects of ANG II on 12-HETE formation in normal and diabetic animals. Both plasma (3.9 +/- 0.9 vs. 0.8 +/- 0.1 ng ANG I.ml-1.h-1, P < 0.01) and tissue (38 +/- 6 vs. 21 +/- 2 ng ANG I.mg tissue-1.h-1, P < 0.05) renin activity levels were markedly reduced in diabetic animals. Iloprost (10(-6) mol/l), a stable analog of prostacyclin, had similar stimulatory effects on renin secretion in both normal and diabetic tissues, but the response was enhanced by LO inhibition in diabetic tissue. 12-HETE (10(-7) mol/l) had an exaggerated effect on renin inhibition in diabetic tissue (78 +/- 2% normal vs. 65 +/- 4% diabetic, P < 0.05). Similarly, ANG II (10(-8) mol/l) inhibition of renin was significantly enhanced in diabetic rats (P < 0.001). However, ANG II did not produce an exaggerated increase in 12-HETE in diabetic renal tissue. Insulin reversed the inhibitory effects of ANG II on renin in normal rats, but it blunted the effect of ANG II in diabetic rats. These studies suggest that, while the capacity of renal cortical tissue to synthesize 12-HETE in response to ANG II is not altered, 12-HETE and ANG II actions are exaggerated in diabetes, and this may contribute to reduced renin production.

Differential short- and long-term effects of insulin on ANG II action in human adrenal glomerulosa cells

Insulin is known to modulate several functions in bovine adrenal cells, including steroidogenesis and growth. However, the role of insulin in regulating aldosterone synthesis in human adrenal glomerulosa cells has not been studied. In the present studies, we have examined the acute and chronic effects of insulin on angiotensin II (ANG II)-induced aldosterone synthesis in cultured normal and adenomatous human adrenal glomerulosa cells. Short-term insulin treatment (1.5 h) resulted in inhibition of ANG II-induced aldosterone synthesis. In contrast, chronic treatment (30 h) resulted in potentiation of ANG II action. The 12-lipoxygenase pathway of arachidonate metabolism has been shown to play a key role in ANG II-induced aldosterone synthesis. The acute inhibitory effects of insulin were in part mediated by inhibition of the 12-lipoxygenase pathway. The chronic stimulatory effect of insulin seemed to be due at least in part to the upregulation of cytochrome P-450 side-chain cleavage enzyme levels. These findings suggest that insulin has a differential temporal effect on ANG II action and therefore may be an important regulator of ANG II-induced aldosterone synthesis in the adrenal.