Cytomegalovirus (CMV)-dependent and -independent changes in the aging of the human immune system: a transcriptomic analysis.

Aging is associated with a profound reduction of the immune capacity (i.e., immunosenescence), which is manifested as increased morbidity and mortality due to infectious diseases in the elderly. The association of cytomegalovirus (CMV) with several aging-associated phenomena has been extensively characterized, e.g., the accumulation of CD8+ nonproliferative, apoptosis-resistant memory cells that have lost the expression of the costimulatory molecule CD28. However, as the CMV seroprevalence is notably high in elderly individuals, the role of CMV-independent changes has been difficult to analyze. To address this question, we performed a transcriptomic analysis (Illumina Human HT12 microarray) of the peripheral blood mononuclear cells (PBMCs) in a cohort of 90-year-old individuals (CMV seronegative, n=6; CMV seropositive, n=140) using the PBMCs of young CMV-seronegative individuals (n=11) as the controls. The cell type distribution (CD3, CD4, CD8, CD28 and CD14) was analyzed using FACS. The data showed that the gene expression profiles of the CMV+ and CMV- nonagenarians were different compared to the CMV- controls. Compared to the CMV- controls, 667 genes showed altered expression in the CMV- nonagenarians, and 559 genes were altered in the CMV+ nonagenarians. Of these, 337 genes were common. An analysis of the canonical pathways revealed that the number of affected pathways was also different (42 in CMV-, 13 in CMV+; of these, 9 were common). Taken together, these results indicate that the CMV-dependent and CMV-independent changes in the aging of the immune system are fundamentally different.

Plasma cell-free DNA levels are elevated in acute Puumala hantavirus infection.

INTRODUCTION: Puumala hantavirus (PUUV) causes a hemorrhagic fever with renal syndrome called nephropathia epidemica (NE). The aim of the present study was to evaluate plasma cell-free DNA (cf-DNA) levels and urinary cf-DNA excretion in acute NE as well as their associations with the severity of the disease. METHODS: Total plasma cf-DNA was quantified directly in plasma of 61 patients and urine of 20 patients with acute NE. We also carried out a qualitative high-sensitivity lab-on-a-chip DNA assay in 20 patients to elucidate the appearance of cf-DNA in plasma and urine. RESULTS: The maximum plasma cf-DNA values taken during acute NE were significantly higher than the control values taken after the hospitalization period (median 1.33 µg/ml, range 0.94-3.29 µg/ml vs. median 0.77 µg/ml, range 0.55-0.99 µg/ml, P<0.001). The maximum plasma cf-DNA levels correlated positively with maximum blood leukocyte count (r = 0.388, P = 0.002) and the length of hospital stay (r = 0.376, P = 0.003), and inversely with minimum blood platelet count (r = -0.297, P = 0.020). Qualitative analysis of plasma cf-DNA revealed that in most of the patients cf-DNA displayed a low-molecular weight appearance, corresponding to the size of apoptotic DNA (150-200 bp). The visually graded maximum cf-DNA band intensity correlated positively with the maximum quantity of total plasma cf-DNA (r = 0.513, P = 0.021). Maximum urinary excretion of cf-DNA in turn was not markedly increased during the acute phase of NE and did not correlate with any of the variables reflecting severity of the disease or with the maximum plasma cf-DNA level. CONCLUSIONS: The plasma levels of cf-DNA are elevated during acute PUUV infection and correlate with the apoptotic cf-DNA-band intensity. The plasma cf-DNA concentration correlates with some variables reflecting the severity of the disease. The urinary excretion of cf-DNA does not reflect the degree of inflammation in the kidney.

Fatal outcome in bacteremia is characterized by high plasma cell free DNA concentration and apoptotic DNA fragmentation: a prospective cohort study.

INTRODUCTION: Recent studies have shown that apoptosis plays a critical role in the pathogenesis of sepsis. High plasma cell free DNA (cf-DNA) concentrations have been shown to be associated with sepsis outcome. The origin of cf-DNA is unclear. METHODS: Total plasma cf-DNA was quantified directly in plasma and the amplifiable cf-DNA assessed using quantitative PCR in 132 patients with bacteremia caused by Staphylococcus aureus, Streptococcus pneumoniae, ß-hemolytic streptococcae or Escherichia coli. The quality of cf-DNA was analyzed with a DNA Chip assay performed on 8 survivors and 8 nonsurvivors. Values were measured on days 1-4 after positive blood culture, on day 5-17 and on recovery. RESULTS: The maximum cf-DNA values on days 1-4 (n = 132) were markedly higher in nonsurvivors compared to survivors (2.03 vs 1.26 ug/ml, p<0.001) and the AUCROC in the prediction of case fatality was 0.81 (95% CI 0.69-0.94). cf-DNA at a cut-off level of 1.52 ug/ml showed 83% sensitivity and 79% specificity for fatal disease. High cf-DNA (>1.52 ug/ml) remained an independent risk factor for case fatality in a logistic regression model. Qualitative analysis of cf-DNA showed that cf-DNA displayed a predominating low-molecular-weight cf-DNA band (150-200 bp) in nonsurvivors, corresponding to the size of the apoptotic nucleosomal DNA. cf-DNA concentration showed a significant positive correlation with visually graded apoptotic band intensity (R = 0.822, p<0.001). CONCLUSIONS: Plasma cf-DNA concentration proved to be a specific independent prognostic biomarker in bacteremia. cf-DNA displayed a predominating low-molecular-weight cf-DNA band in nonsurvivors corresponding to the size of apoptotic nucleosomal DNA.