Studies have shown that chronic inflammatory disorders, such as rheumatoid arthritis, systemic lupus erythematosus, and psoriasis are associated with an increased risk of atherosclerotic ...cardiovascular disease. The mechanism by which inflammation increases cardiovascular disease is likely multifactorial but changes in HDL structure and function that occur during inflammation could play a role.
HDL levels decrease with inflammation and there are marked changes in HDL-associated proteins. Serum amyloid A markedly increases whereas apolipoprotein A-I, lecithin:cholesterol acyltransferase, cholesterol ester transfer protein, paraoxonase 1, and apolipoprotein M decrease. The exact mechanism by which inflammation decreases HDL levels is not defined but decreases in apolipoprotein A-I production, increases in serum amyloid A, increases in endothelial lipase and secretory phospholipase A2 activity, and decreases in lecithin:cholesterol acyltransferase activity could all contribute. The changes in HDL induced by inflammation reduce the ability of HDL to participate in reverse cholesterol transport and protect LDL from oxidation.
During inflammation multiple changes in HDL structure occur leading to alterations in HDL function. In the short term, these changes may be beneficial resulting in an increase in cholesterol in peripheral cells to improve host defense and repair but over the long term these changes may increase the risk of atherosclerosis.
Background Despite improvements in survival with human immunodeficiency virus (HIV) infection, kidney disease remains an important complication. Few studies have evaluated risk factors associated ...with the development of end-stage renal disease (ESRD) in HIV-infected individuals. We sought to identify traditional and HIV-related risk factors for ESRD in HIV-infected individuals and compare ESRD risk by estimated glomerular filtration rate (eGFR) and proteinuria levels. Study Design Retrospective cohort study. Setting & Participants 22,156 HIV-infected veterans without pre-existing ESRD receiving health care in the Veterans' Affairs medical system between 1996 and 2004. Predictors Hypertension, diabetes, cardiovascular disease, hypoalbuminemia (serum albumin <3.5 mg/dL), CD4 lymphocyte count, HIV viral load, hepatitis C virus coinfection, proteinuria, and eGFR were identified using the Veterans' Affairs electronic record system. Outcomes ESRD was ascertained by the US Renal Data System. Results 366 cases of ESRD occurred, corresponding to 3 cases/1,000 person-years. Hypertension (HR, 1.9; 95% CI, 1.5-2.4), diabetes (HR, 1.7; 95% CI, 1.3-2.2), and cardiovascular disease (HR, 2.2; 95% CI, 1.7-2.7) were associated independently with ESRD risk in multivariate-adjusted models, as were CD4 lymphocyte count <200 cells/μL (HR, 1.5; 95% CI, 1.2-2.0), HIV viral load ≥30,000 copies/mL (HR, 2.0; 95% CI, 1.5-2.8), hepatitis C virus coinfection (HR, 1.9; 95% CI, 1.5-2.4), and hypoalbuminemia (HR, 2.1; 95% CI, 1.8-2.5). Compared with persons without chronic kidney disease, defined as eGFR >60 mL/min/1.73 m2 and no proteinuria, lower eGFR and higher proteinuria categories were associated jointly with exponentially higher ESRD rates, ranging from 6.6 events/1,000 person-years for persons with urine protein excretion of 30-100 mg/dL and eGFR >60 mL/min/1.73 m2 to 193 events/1,000 person-years for persons with urine protein excretion ≥300 mg/dL and eGFR <30 mL/min/1.73 m2. Limitations Results may not be generalizable to female and nonveteran populations. Conclusions In HIV-infected persons, ESRD risk appears attributable to a combination of traditional and HIV-related risk factors for kidney disease. Combining eGFR and proteinuria for chronic kidney disease staging is most effective for stratifying the risk of ESRD.
Many of the beneficial and adverse effects of niacin are mediated via a G protein receptor, G protein-coupled receptor 109A/hydroxycarboxylic acid 2 receptor (GPR109A/HCA2), which is highly expressed ...in adipose tissue and macrophages. Here we demonstrate that immune activation increases GPR109A/HCA2 expression. Lipopolysaccharide (LPS), TNF, and interleukin (IL) 1 increase GPR109A/HCA2 expression 3- to 5-fold in adipose tissue. LPS also increased GPR109A/HCA2 mRNA levels 5.6-fold in spleen, a tissue rich in macrophages. In peritoneal macrophages and RAW cells, LPS increased GPR109A/HCA2 mRNA levels 20- to 80-fold. Zymosan, lipoteichoic acid, and polyinosine-polycytidylic acid, other Toll-like receptor activators, and TNF and IL-1 also increased GPR109A/HCA2 in macrophages. Inhibition of the myeloid differentiation factor 88 or TIR-domain-containing adaptor protein inducing IFNβ pathways both resulted in partial inhibition of LPS stimulation of GPR109A/HCA2, suggesting that LPS signals an increase in GPR109A/HCA2 expression by both pathways. Additionally, inhibition of NF-κB reduced the ability of LPS to increase GPR109A/HCA2 expression by ∼50% suggesting that both NF-κB and non-NF-κB pathways mediate the LPS effect. Finally, preventing the LPS-induced increase in GPR109A/HCA2 resulted in an increase in TG accumulation and the expression of enzymes that catalyze TG synthesis. These studies demonstrate that inflammation stimulates GPR109A/HCA2 and there are multiple intracellular signaling pathways that mediate this effect. The increase in GPR109A/HCA2 that accompanies macrophage activation inhibits the TG accumulation stimulated by macrophage activation.
TLR activation by multiple pathways leads to triglyceride accumulation in macrophages that could contribute to the accelerated atherosclerosis seen in chronic infections and inflammatory diseases.
...LPS treatment of macrophages induces TG accumulation, which is accentuated by TG‐rich lipoproteins or FFA. We defined pathways altered during macrophage activation that contribute to TG accumulation. Glucose uptake increased with activation, accompanied by increased GLUT1. Oxidation of glucose markedly decreased, whereas incorporation of glucose‐derived carbon into FA and sterols increased. Macrophage activation also increased uptake of FFA, associated with an increase in CD36. Oxidation of FA was markedly reduced, whereas the incorporation of FA into TGs increased, associated with increased GPAT3 and DGAT2. Additionally, macrophage activation decreased TG lipolysis; however, expression of ATGL or HSL was not altered. Macrophage activation altered gene expression similarly when incubated with exogenous FA or AcLDL. Whereas activation with ligands of TLR2 (zymosan), TLR3 (poly I:C), or TLR4 (LPS) induced alterations in macrophage gene expression, leading to TG accumulation, treatment of macrophages with cytokines had minimal effects. Thus, activation of TLRs leads to accumulation of TG in macrophages by multiple pathways that may have beneficial effects in host defense but could contribute to the accelerated atherosclerosis in chronic infections and inflammatory diseases.
Context:
An increasing number of studies suggest that bone marrow adipose tissue (BMAT) might play a role in the pathogenesis of osteoporosis. Our previous study of Caucasian women demonstrated that ...there is an inverse relationship between BMAT and whole-body bone mineral density (BMD). It is unknown whether visceral adipose tissue (VAT), sc adipose tissue (SAT), and skeletal muscle had an effect on the relationship between BMAT and BMD.
Objective:
In the present study we investigated the relationship between pelvic, hip, and lumbar spine BMAT with hip and lumbar spine BMD in the population-based Coronary Artery Risk Development in Young Adults (CARDIA) sample with adjustment for whole-body magnetic resonance imaging (MRI)-measured VAT, SAT, and skeletal muscle.
Design:
T1-weighted MRI was acquired for 210 healthy African-American and Caucasian men and women (age 38–52 yr). Hip and lumbar spine BMD were measured by dual-energy x-ray absorptiometry.
Results:
Pelvic, hip, and lumbar spine BMAT had negative correlations with hip and lumbar spine BMD (r = −0.399 to −0.550, P < 0.001). The inverse associations between BMAT and BMD remained strong after adjusting for demographics, weight, skeletal muscle, SAT, VAT, total adipose tissue (TAT), menopausal status, lifestyle factors, and inflammatory markers (standardized regression coefficients = −0. 296 to −0.549, P < 0.001). Among body composition measures, skeletal muscle was the strongest correlate of BMD after adjusting for BMAT (standardized regression coefficients = 0.268–0.614, P < 0.05), with little additional contribution from weight, SAT, VAT, or total adipose tissue.
Conclusion:
In this middle-aged population, a negative relationship existed between MRI-measured BMAT and hip and lumbar spine BMD independent of demographics and body composition. These observations support the growing evidence linking BMAT with low bone density.
C-reactive protein (CRP) levels>3 mg/L and>10 mg/L are associated with high and very high cardiovascular risk, respectively, in the general population. Because rheumatoid arthritis (RA) confers ...excess cardiovascular mortality, we determined the prevalence of these CRP levels among RA patients stratified on the basis of their RA disease activity.
We evaluated physician and patient global assessments of disease activity, tender and swollen 28 joint counts, erythrocyte sedimentation rate (ESR), and CRP measured in a single clinic visit for 151 RA patients. Disease activity was calculated using the Clinical Disease Activity Index (CDAI) and the Disease Activity Score 28 Joints (DAS28-ESR and DAS28-CRP).
Median CRP level was 5.3 mg/L. 68% of patients had CRP>3 mg/L, and 25% had CRP>10 mg/L. Of those with 0-1 swollen joints (n = 56), or 0-1 tender joints (n = 81), 64% and 67%, respectively, had CRP>3 mg/L, and 23% and 20%, respectively, had CRP>10 mg/L. Of those with remission or mildly active disease by CDAI (n = 58), DAS28-ESR (n = 39), or DAS28-CRP (n = 70), 49-66% had CRP>3 mg/L, and 10-14% had CRP>10 mg/L. Of patients with moderate disease activity by CDAI (n = 51), DAS28-ESR (n = 78), or DAS28-CRP (n = 66), 67-73% had CRP>3 mg/L, and 25-33% had CRP>10 mg/L.
Even among RA patients whose disease is judged to be controlled by joint counts or standardized disease scores, a substantial proportion have CRP levels that are associated high or very high risk for future cardiovascular events in the general population.
Cardiovascular disease (CVD) is an increasing cause of morbidity and mortality in HIV-infected patients. However, it is controversial whether HIV infection contributes to accelerated atherosclerosis ...independent of traditional CVD risk factors.
Cross-sectional study of HIV-infected participants and controls without pre-existing CVD from the study of Fat Redistribution and Metabolic Change in HIV Infection (FRAM) and the Multi-Ethnic Study of Atherosclerosis (MESA). Preclinical atherosclerosis was assessed by carotid intima-medial thickness (cIMT) measurements in the internal/bulb and common regions in HIV-infected participants and controls after adjusting for traditional CVD risk factors.
For internal carotid, mean IMT was 1.17 +/- 0.50 mm for HIV-infected participants and 1.06 +/- 0.58 mm for controls (P < 0.0001). After multivariable adjustment for demographic characteristics, the mean difference of HIV-infected participants vs. controls was 0.188 mm 95% confidence interval (CI) 0.113-0.263, P < 0.0001. Further adjustment for traditional CVD risk factors modestly attenuated the HIV association (0.148 mm, 95% CI 0.072-0.224, P = 0.0001). For the common carotid, HIV infection was independently associated with greater IMT (0.033 mm, 95% CI 0.010-0.056, P = 0.005). The association of HIV infection with IMT was similar to that of smoking, which was also associated with greater IMT (internal 0.173 mm, common 0.020 mm).
Even after adjustment for traditional CVD risk factors, HIV infection was accompanied by more extensive atherosclerosis measured by IMT. The stronger association of HIV infection with IMT in the internal/bulb region compared with the common carotid may explain previous discrepancies in the literature. The association of HIV infection with IMT was similar to that of traditional CVD risk factors, such as smoking.
Background Compared with controls, human immunodeficiency virus (HIV)-infected persons have a greater prevalence of kidney disease, assessed according to high cystatin C level and albuminuria, but ...not according to creatinine level. However, the clinical importance of increased cystatin C level and albuminuria in the HIV-infected population has not been studied. Study Design We conducted an observational cohort study to determine the association of kidney disease (measured according to albuminuria, cystatin C, and serum creatinine) with mortality. Setting & Participants 922 HIV-infected persons enrolled in the FRAM (Fat Redistribution and Metabolic Change in HIV Infection) Study. Predictor Serum cystatin C and serum creatinine levels were used to estimate glomerular filtration rates (eGFRSCysC and eGFRSCr , respectively). Albuminuria was defined as a positive urine dipstick result (≥1+) or urine albumin-creatinine ratio >30 mg/g. Outcome 5-Year mortality. Results At baseline, decreased kidney function (eGFRSCysC <60 mL/min/1.73 m2 ) or albuminuria was present in 28% of participants. After 5 years of follow-up, mortality was 48% in those with both eGFRSCysC <60 mL/min/1.73 m2 and albuminuria, 23% in those with eGFRSCysC <60 mL/min/1.73 m2 alone, 20% in those with albuminuria alone, and 9% in those with neither condition. After multivariable adjustment for demographics, cardiovascular risk factors, HIV-related factors, and inflammatory marker levels, eGFRSCysC <60 mL/min/1.73 m2 and albuminuria were associated with a nearly 2-fold increase in mortality, whereas eGFRSCr <60 mL/min/1.73m2 did not appear to have a substantial association with mortality. Together, eGFRSCysC <60 mL/min/1.73 m2 and albuminuria accounted for 17% of the population-level attributable risk of mortality. Limitations Vital status was unknown in 261 participants from the original cohort. Conclusions Kidney disease marked by albuminuria or increased cystatin C level appears to be an important risk factor for mortality in HIV-infected individuals. A substantial proportion of this risk may be unrecognized because of the current reliance on serum creatinine to estimate kidney function in clinical practice.
The acute phase response (APR) produces marked alterations in lipid and carbohydrate metabolism including decreasing plasma ketone levels. Fibroblast growth factor 21 (FGF21) is a recently discovered ...hormone that regulates lipid and glucose metabolism and stimulates ketogenesis. Here we demonstrate that lipopolysaccharide (LPS), zymosan, and turpentine, which induce the APR, increase serum FGF21 levels 2-fold. Although LPS, zymosan, and turpentine decrease the hepatic expression of FGF21, they increase FGF21 expression in adipose tissue and muscle, suggesting that extrahepatic tissues account for the increase in serum FGF21. After LPS administration, the characteristic decrease in plasma ketone levels is accentuated in FGF21−/− mice, but this is not due to differences in expression of carnitine palmitoyltransferase 1α or hydroxymethyglutaryl-CoA synthase 2 in liver, because LPS induces similar decreases in the expression of these genes in FGF21−/− and control mice. However, in FGF21−/− mice, the ability of LPS to increase plasma free fatty acid levels is blunted. This failure to increase plasma free fatty acid could contribute to the accentuated decrease in plasma ketone levels because the transport of fatty acids from adipose tissue to liver provides the substrate for ketogenesis. Treatment with exogenous FGF21 reduced the number of animals that die and the rapidity of death after LPS administration in leptin-deficient ob/ob mice and to a lesser extent in control mice. FGF21 also protected from the toxic effects of cecal ligation and puncture-induced sepsis. Thus, FGF21 is a positive APR protein that protects animals from the toxic effects of LPS and sepsis.
Inflammation produces marked changes in lipid metabolism, including increased serum fatty acids (FAs) and triglycerides (TGs), increased hepatic TG production and VLDL secretion, increased adipose ...tissue lipolysis, and decreased FA oxidation in liver and heart. Lipopolysaccharide (LPS) also increases TG and cholesteryl ester levels in kidneys. Here we confirm these findings and define potential mechanisms. LPS decreases renal FA oxidation by 40% and the expression of key proteins required for oxidation of FAs, including FA transport protein-2, fatty acyl-CoA synthase, carnitine palmitoyltransferase-1, medium-chain acyl-CoA dehydrogenase, and acyl-CoA oxidase. Similar decreases were observed in peroxisome proliferator-activated receptor α (PPARα)-deficient mice. LPS also caused a reduction in renal mRNA levels of PPARα (75% decrease), thyroid hormone receptor α (TRα) (92% decrease), and TRβ (84% decrease), whereas PPARβ/δ and γ were not altered. Expression of PGC1 α and β, coactivators required for PPARs and TR, was also decreased in kidneys of LPS-treated mice, as were mitochondrial genes regulated by PGC1 (Atp5g1, COX5a, Idh3a, and Ndufs8). Decreased renal FA oxidation could be a by-product of the systemic coordinated host response to increase FAs and TGs available for host defense and/or tissue repair. However, the kidney requires energy to support its transport functions, and the inability to generate energy via FA oxidation might contribute to the renal failure seen in severe sepsis.
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