Plasma Levels of Soluble CD14 (activation marker)
Predict Mortality in HIV Infection
Reported by Jules Levin
CROI 2010 Feb 16-19 SF
Netanya Sandler*1, H Wand2, D Nixon3, C Pedersen4, K Ruxrungtham5, S Lewin6, S Emery2, S Deeks7, I Sereti8, D Douek1, and SMART INSIGHT Group
1Vaccine Res Ctr, NIAID, NIH, Bethesda, MD, US; 2Natl Ctr in HIV Epi and Clin Res, Univ of New South Wales, Sydney, Australia; 3Virginia Commonwealth Univ, Richmond, US; 4Odense Univ Hosp, Denmark; 5HIVNAT Res Collaboration, Thai Red Cross AIDS Res Ctr and Chulalongkorn Univ, Bangkok; 6Monash Univ, The Alfred Hosp and Burnet Inst, Melbourne, Australia; 7Univ of California, San Francisco, US; and 8NIAID, NIH, Bethesda, MD, US
Baseline plasma levels of soluble CD14 a marker of monocyte activation in response to LPS, predict mortality in HIV infection.
LPS was not associated with mortality, suggesting it may be the monocyte responsiveness to LPS, not PS itself, that is associated with death.
sCD14 was associated with mortality independent of other risk factors of death, independent of CD4 T cell count and HIV viral load, and independent of the markers of inflammation and activation of he coagulation cascade previously associated with mortality.
The association od sCD14 with mortality was present regardless of whether subjects were on continuous or intermittent ART.
Intestinal fatty acid binding protein, reflective of enterocyte apoptosis, tended to be higher in subjects who died, suggesting that ongoing intestinal damage was occurring in these patients.
There was a trend towards increased mortality in subjects with higher quartiles of I-FABP levels, suggesting that ongoing intestinal damage may be associated with mortality.
Given the association of sCD14 and IL-6 with mortality, attenuation of intestinal damage and the immune system’s response to microbial translocation may improve may improve clinical outcome in patients with HIV infection.
Background: HIV infection causes increased intestinal permeability, microbial translocation and chronic systemic immune activation. In order to define the long-term consequences of this process, we investigated the relationship of baseline biomarkers of microbial translocation with all-cause mortality.
Methods: In the Strategies for Management of Antiretroviral Therapy (SMART) trial, patients with CD4+ T cell counts >350/mm3 were randomized to a viral suppression arm with continuous antiretroviral therapy (VS) or a drug conservation arm (DC) with episodic antiretroviral therapy (ART) based on CD4+ T cell count. Using stored baseline plasma specimens, a nested case-control study was performed for 74 of the 85 patients who died and had available plasma and 128 controls matched on age, country, sex, and enrollment date. Five biomarkers were studied: soluble CD14 (sCD14), endotoxin core antibody (EndoCAb), and intestinal fatty acid binding protein (I-FABP) were assessed by ELISA; lipopolysaccharide (LPS) by the limulus amebocyte lysate assay; and 16S ribosomal DNA (16S rDNA) by quantitative PCR. The association of each biomarker with mortality was assessed using conditional logistic regression by categorizing biomarkers into quartiles. Odds ratios (ORs) with 95% confidence intervals (CI) and p-values of each of the top 3 quartiles versus the lowest quartile were calculated.
Results: Patients in the highest quartile of LPS bioactivity, with sCD14 levels >2.71x106 pg/mL, had an OR of death of 6.0 versus the lowest quartile with levels <2.01x106 pg/mL (see table).
Several adjustments performed for baseline covariates, including previously identified risk factors for death; CD4+ T cell count and HIV viral load; and interleukin-6, high sensitivity C-reactive protein, serum amyloid A, and D-dimer, did not substantially alter the associations. The association of sCD14 with death was similar for the DC and VS groups (OR were 3.7 and 2.0, respectively; P =0.43 for the difference). Other markers were not significantly associated with death, although there was a trend towards increased mortality in patients with higher I-FABP levels (OR=1.9, 95%CI 0.9 to 3.8, P =0.09).
Conclusions: Among patients with HIV infection, greater monocyte responsiveness to LPS, exhibited by high sCD14 levels, is associated with all-cause mortality, but other biomarkers of microbial translocation are not related to all-cause mortality.
5,472 HIV+ subjects at 318 sites in 33 countries
- CD4+ T cells > 350 cells/mm3at enrollment with >80% on antiretroviral therapy
- Viral suppression (VS): Continuous use of ART
- Drug conservation (DC): Start treatment when CD4+ T cells < 250 cells/mm3 and continue until CD4+ T cells > 350 cells/mm3
85 subjects died, with a hazard ratio (DC/VS) of death of 1.8 (95% CI: 1.2-2.9, P=0.007)1
IL-6, C-reactive protein, serum amyloid A, and D-dimer were associated with mortality2
LPS stimulates production of IL-6, CRP3, serum amyloid A4, and tissue factor, leading to D-dimer production5
Microbial translocation, i.e. LPS and 16S ribosomal DNA, correlates with systemic immune activation in HIV infection6,7
LPS stimulates monocytes to secrete and shed sCD148
- sCD14 facilitates LPS-mediated activation of endothelial cells and dendritic cells
- sCD14 may also facilitate LPS clearance
Baseline plasma samples available from 74 patients who died were matched with 2 controls on age, sex, location, date of enrollment
Soluble CD14 (sCD14), endotoxin core IgM antibody (EndoCAb), and intestinal fatty acid binding protein (I-FABP) were assessed byELISA
Lipopolysaccharide (LPS) was evaluated with the Limulus Amebocyte Lysate assay
16S ribosomal DNA (16S rDNA) was determined by quantitative polymerase chain reaction
Conditional logistic regression analysis for matched case-control studies was used to assess associations of each baseline biomarker with subsequent mortality.
Analyses by quartiles of each biomarker were also performed, and odds ratios (ORs) along with 95% confidence intervals (CI) and p-values for each of the three upper quartiles versus the lowest quartile (reference group) were assessed.
ORs were adjusted for risk factors of mortality (p≤0.10), including age, hepatitis co-infection, prior CVD, smoking, prior diabetes and baseline CD4+ cell count, or for markers of inflammation and activation of coagulation pathways (interleukin-6, high sensitivity C-reactive protein, serum amyloid A, and D-dimer)
Subjects who died were older, had lower baseline CD4 T cell counts, were co-infected with hepatitis B/C, smoked, had diabetes, took blood pressure lowering drugs, had prior cardiovascular disease, and had lower LDL cholesterol.
Subjects who died had significantly higher sCD14 levels and non-significantly higher I-FABP levels than their matched controls. No other differences were noted for the various biomarkers measured. sCD14 conferred a 6-fold increased risk of mortality in subjects with the top quartile of levels compared to the lowest quartile. I-FABP levels also conferred a non-significant 1.9-fold increased risk of mortality when comparing the highest to the lowest quartile.
Higher sCD14 levels conferred a significantly increased risk of mortality in the drug conservation (DC) arm. The risk conferredby higher sCD14 levels was also elevated in the viral suppression (VS) arm but was not statistically significant. However, the p-value for the interaction was 0.43, suggesting that the treatment arm to which the subjects were randomized did not affect the risk associatedwith higher sCD14 levels. No other marker conferred an increased risk of death in either treatment arm.
A. Subjects with the highest quartile of sCD14 levels, a marker of LPS bioactivity, had a 6-fold higher rate of death compared to those with the lowest quartile of sCD14 levels. This increased mortality was observed even after adjusting for other established risk factors for death, for markers of inflammation and activation of coagulation pathways, and for baseline CD4 T cell countand HIV RNA levels, suggesting that plasma sCD14 levels independently predict mortality in HIV infection.
B. Subjects with the highest quartile of I-FABP levels, a marker of enterocyte apoptosis, had a non-significant increased risk of death compared to those with the lowest quartile of I-FABP levels, and this trend persisted after adjustment for risk factors ofdeath and markers of inflammation and activation of coagulation pathways.
1The Strategies for Management of Antiretroviral Therapy (SMART) Study Group. N EnglJ Med 2006;355:2283-96.
2Kuller, L.H. et al. Inflammatory and coagulation biomarkers and mortality in patients with HIV infection. PLoSMed. 2008;5(10):e203.
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4Migita, K. et al. Lipopolysaccharidesignaling induces serum amyloidA (SAA) synthesis in human hepatocytesin vitro. FEBS Lett. 2004; 569(1-3):235-9.
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6Brenchley, J.M. et al. Microbial translocation is a cause of systemic immune activation in chronic HIV infection. Nat Med. 2006;12(12):1365-71.
7Jiang, W. et al. Plasma levels of bacterial DNA correlate with immune activation and the magnitude of immune restoration in persons with antiretroviral-treated HIV infection. J Infect Dis. 2009;199(8):1177-85.
8Landmann, R. et al. Human monocyteCD14 is upregulatedby lipopolysaccharide. Infect Immun. 1996 May;64(5):1762-9.