Human cytomegalovirus infection and antiviral immunity in septic patients without canonical immunosuppression

Refining human T-cell immunotherapy of cytomegalovirus disease: a mouse model with 'humanized' antigen presentation as a new preclinical study tool

With the cover headline 'T cells on the attack,' the journal Science celebrated individualized cancer immunotherapy by adoptive transfer of T cells as the 'Breakthrough of the Year' 2013 (J. Couzin-Frankel in Science 342:1432-1433, 2013). It is less well recognized and appreciated that individualized T cell immunotherapy of cytomegalovirus (CMV) infection is approaching clinical application for preventing CMV organ manifestations, interstitial CMV pneumonia in particular. This coincident medical development is particularly interesting as reactivated CMV infection is a major viral complication in the state of transient immunodeficiency after the therapy of hematopoietic malignancies by hematopoietic cell transplantation (HCT). It may thus be attractive to combine T cell immunotherapy of 'minimal residual disease/leukemia (MRD)' and CMV-specific T cell immunotherapy to combat both risks in HCT recipients simultaneously, and ideally with T cells derived from the respective HLA-matched HCT donor. Although clinical trials of human CMV-specific T cell immunotherapy were promising in that the incidence of virus reactivation and disease was found to be reduced with statistical significance, animal models are still instrumental for providing 'proof of concept' by directly documenting the prevention of viral multiple-organ histopathology and organ failure under controlled conditions of the absence versus presence of the therapy, which obviously is not feasible in an individual human patient. Further, animal models can make predictions regarding parameters that determine the efficacy of T cell immunotherapy for improved study design in clinical investigations, and they allow for manipulating host and virus genetics. The latter is of particular value as it opens the possibility for epitope specificity controls that are inherently missing in clinical trials. Here, we review a recently developed new mouse model that is more approximated to human CMV-specific T cell immunotherapy by 'humanizing' antigen presentation using antigenically chimeric CMV and HLA-transgenic mice to allow for an in vivo testing of the antiviral function of human CMV-specific T cells. As an important new message, this model predicts that T cell immunotherapy is most efficient if CD4 T cells are equipped with a transduced TCR directed against an epitope presented by MHC/HLA class-I for local delivery of 'cognate' help to CD8 effector T cells at infected MHC/HLA class-II-negative host tissue cells.

Sepsis and cytomegalovirus: foes or conspirators?

Cytomegalovirus (CMV) reactivation in non-immune-suppressed critically ill patients is an area of increasing interest. CMV has long been appreciated as a pathogen in immunocompromised hosts. CMV reactivates in approximately one-third of latently infected non-immune-suppressed hosts during critical illness; however, its role as a pathogen in these patients remains unclear. CMV reactivation has been linked to bacterial sepsis and likely results from inflammation, transient immune compromise, and viral epigenetic changes. While CMV may improve immune response to some bacterial infections, other data suggest that CMV induces exaggerated responses to severe infections that may be harmful to latently infected hosts. These results also suggest that previous infection history may explain significant differences seen between human septic responses and murine models of sepsis. While critically ill human hosts clearly have worse outcomes associated with CMV reactivation, determining causality remains an area of investigation, with randomized control trials currently being performed. Here we review the current literature and highlight areas for future investigation.

Interferon-γ production by natural killer cells and cytomegalovirus in critically ill patients

OBJECTIVE

The mechanisms involved in cytomegalovirus reactivation in critically ill patients who were previously immunocompetent are still unknown. The current study was designed to evaluate the possible role of natural killer cells in the reactivation of cytomegalovirus in these patients.

DESIGN

Prospective observational.

SETTING

: A medical intensive care unit of a university hospital.

PATIENTS

Fifty-one subjects, including 15 patients who experienced cytomegalovirus reactivation (cases) during their intensive care unit stay and 15 patients who matched intensive care unit controls, selected from a cohort of consecutive nonimmunocompromised intensive care unit patients, as well as healthy controls.

INTERVENTIONS

Tests included weekly systematic immunomonitoring and routine screening for cytomegalovirus infection until discharge from the intensive care unit or death. The immunophenotype and functions of natural killer cells were performed by flow cytometry, and serum levels of pro- and anti-inflammatory cytokines were determined by enzyme-linked immunosorbent assay.

MEASUREMENTS AND MAIN RESULTS

The overall occurrence of cytomegalovirus reactivation in the cohort was 27%. No differences of natural killer cell effector functions were observed at admission between cases and controls. Instead, before cytomegalovirus reactivation, the ability of natural killer cells to secrete interferon-γ was significantly reduced in cases as compared with controls upon stimulation with antibody-coated target cells (p = .029) and with K562 cell stimulation (p = .029). No phenotypic or quantitative differences were observed between cases and controls. Cases exhibited higher levels of interleukin 10 (p = .031) and interleukin 15 (p = .021) than controls before cytomegalovirus reactivation.

CONCLUSIONS

Impaired natural killer cell function with reduced interferon-γ secretion precedes the occurrence of cytomegalovirus reactivation among previously immunocompetent critically ill patients.

Aqueous cytokine changes associated with Posner-Schlossman syndrome with and without human cytomegalovirus

AIM

To study the differences in aqueous cytokines in Posner-Schlossman Syndrome (PSS) patients with and without human cytomegalovirus (CMV) DNA in the aqueous humor.

METHODS

This is a prospective study. Fifty-three uveitis patients with clinical signs of PSS were enrolled and aqueous humor samples were collected. Fourteen PSS patients were positive of CMV DNA in the aqueous by polymerase chain reaction (PCR) analysis. These eyes were negative of common ocular pathogens such as herpes simplex virus, varicella-zoster virus, rubella virus and toxoplasma. Twenty-five otherwise healthy cataract patients were enrolled as controls. Cytokine concentration was measured by a magnetic color-bead-based multiplex assay and analyzed using statistical and classification approaches.

RESULTS

The average age of 53 PSS patients was 48.74±13.43 years (yrs) (mean ± standard deviation) and 66.3±15.0 yrs for the controls. The median CMV viral DNA copy number was 26000/mL aqueous (range 1400 to 85000 copies/mL) in 14 CMV positive patients as determined by quantitative PCR. PSS aqueous had significantly higher Interleukin (IL)-8 (CXCL8), monocyte chemotactic protein-1 (CCL2), macrophage inhibitory protein 1-β (CCL4), granulocyte colony-stimulating factor (GCSF) and transforming growth factor-β (TGF-β) levels than controls after adjusted by age and gender. IL-2, IL-12, tumor necrosis factor-α (TNF-α) and interferon-α (IFN-α) levels were significantly lower in PSS aqueous than controls. No difference between CMV positive PSS and CMV negative PSS aqueous was observed. Over 97% of PSS samples were distinguished from controls by elevated CXCL10 (>500 ng/mL), CXCL8 (>30 ng/mL) and CCL2 (>60 ng/mL) levels.

CONCLUSION

PSS eyes were characterized by elevated aqueous chemokine concentration. The presence of CMV viral DNA was not associated with significant change of the type of cytokine expression in PSS patients.

Cytomegalovirus reactivation in critically ill immunocompetent hosts: a decade of progress and remaining challenges

Human cytomegalovirus (HCMV) is an undisputed pathogen in humans with severe immune compromise, which has historically been thought to carry little consequence in immunocompetent hosts. During the past decade, however, accumulating data suggest that significant numbers of immunocompetent humans reactivate HCMV during critical illness, and that these reactivation episodes are associated with worsened outcomes. Because most people are infected with this ubiquitous virus by adulthood, confirming pathogenicity has now become a clinical priority. In this article, we will review the incidence and implications of reactivation, the relevant immune responses and reactivation triggers relevant to the immunocompetent host. We will summarize the progress made during the past ten years, outline the work ongoing in this field, and identify the major gaps remaining in our emerging understanding of this phenomenon.

Oncomodulation by human cytomegalovirus: novel clinical findings open new roads

The question whether human cytomegalovirus may affect cancer diseases has been discussed (very controversially) for decades. There are convinced believers and strict opponents of the idea that HCMV might be able to play a role in the course of cancer diseases. In parallel, the number of published reports on the topic is growing. Recently published and presented (Ranganathan P, Clark P, Kuo JS, Salamat S, Kalejta RF. A Survey of Human Cytomegalovirus Genomic Loci Present in Glioblastoma Multiforme Tissue Samples. 35th Annual International Herpes Workshop, Salt Lake City, 2010) data on HCMV detection in glioblastoma tissues and colocalisation of HCMV proteins with cellular proteins known to be relevant for glioblastoma progression motivated us to recapitulate the current state of evidence.

Virological and immunological features of active cytomegalovirus infection in nonimmunosuppressed patients in a surgical and trauma intensive care unit

Cytomegalovirus (CMV) reactivation occurs frequently in critically ill patients. The natural course of CMV infection and the interaction between CMV and the adaptive immune system in this setting remain poorly defined. Fifty-three CMV-seropositive patients in a surgical and trauma intensive care unit were included in this study. The CMV DNA load in tracheal aspirates (TA) and plasma (PL) was monitored by qPCR. CMV-specific T-cell immunity was assessed by intracellular cytokine staining. Plasma TNF-alpha levels were determined by ELISA. CMV reactivation occurred in 39.7% of patients (23% had CMV DNA detected only in TA). The analysis of TA allowed an earlier diagnosis in 28% of patients. Clearance of CMV DNAemia preceded that of CMV DNA in TA in some episodes. Peak CMV DNA levels were significantly higher in TA than in PL (P = 0.02). CMV reactivation developed in the presence of CMV-specific T cells. Termination of CMV reactivation was associated with an expansion of functional CMV-specific T cells. Plasma levels of TNF-alpha did not allow for the prediction of the occurrence of CMV reactivation. CMV-specific T-cell immunity is preserved in most critically ill patients experiencing CMV reactivation. Analysis of respiratory specimens is imperative for an optimal monitoring of CMV reactivation in this setting.

Neutrophil-derived circulating free DNA (cf-DNA/NETs), a potential prognostic marker for mortality in patients with severe burn injury

The predictive value of circulating free DNA/neutrophil extracellular traps (cf-DNA/NETs) has recently been shown in patients with major trauma for sepsis, multiple organ failure, and mortality. Here we report on the predictive potential of cf-DNA/NETs for mortality in patients with severe burn injury. In a prospective study 32 patients with severe burn injury were included. Blood samples were sequentially obtained on day 1, 3, 5, and 7 after admission. cf-DNA/NETs was directly quantified from plasma by means of rapid fluorescence assay. Time kinetics of cf-DNA/NETs were correlated with clinical data, C-reactive protein (CRP), procalcitonin (PCT), and interleukin (IL)-6. Furthermore sensitivity, specificity, and positive and negative predictive value, as well as receiver operation characteristic (ROC) curves were calculated. Seven patients died within the first month after burn injury. cf-DNA/NETs values from these patients were significantly increased already on day 1 and 3 after admission compared with patients who survived (p < 0.01). In contrast, PCT levels of nonsurvivors were significantly elevated on day 3 and 5 (p < 0.01), while CRP and IL-6 did not show any significant difference between survivors and nonsurvivors. At a cutoff of 255 ng/ml, cf-DNA/NETs had sensitivity of 0.8 and specificity of 0.74. ROC revealed largest areas under the curve (AUC) for cf-DNA/NETs on day 1 (0.851) and 3 (0.883) after admission. For all values between day 1 and 7, AUC was 0.815. cf-DNA/NETs seems to be a rapid, valuable marker for prediction of mortality in burn patients. A larger confirmation trial ought to be carried out.

Epidemiology of human cytomegalovirus (HCMV) in an urban region of Germany: what has changed?

Since the dynamics of transmission of human cytomegalovirus (HCMV) have not been clarified yet, we assessed a possible change in HCMV seroprevalence in Frankfurt am Main, Germany during the past twenty years and tried to detect variables with an impact on epidemiology. Between 1/1/1988 and 10/15/2008, a total of 54443 serum samples were collected for routine diagnostics and analyzed using Enzygnost Anti HCMV-IgG enzyme immunoassay (Siemens/Dade Behring, Marburg, Germany). Two decades, 1/1/1988-12/31/1997 and 1/1/1998-10/15/2008, and several groups (type of health insurance, gender, age, HIV-status) were evaluated to assess changes in seroprevalence. Regarding both decades, the overall age-adjusted prevalence of HIV-negative patients dropped from 63.70% (confidence interval (CI) 95% 63.15-64.25) to 57.25% (CI 95% 56.57-57.93; P < 0.0001). Private health insurance (PHI) patients showed significant lower HCMV seroprevalences than members of obligatory health insurances (OHI) in both decades (1988-1997: PHI = 55.79%, OHI = 64.27%; P < 0.0001; 1998-1908: PHI = 47.02%, OHI = 58.74%; P < 0.0001). Furthermore, comparing the two decades, there was generally a gender-specific statistically significant decrease in HCMV seroprevalence for males (63.54-55.54%) and females (63.83-58.73%) as well as for members of PHI and OHI (PHI males: 57.59% to 47.19%, PHI females 54.10-46.80%; OHI males: 64.00-57.06%, OHI females 64.50-60.11%). Also, while female HIV-positive patients showed significant difference in HCMV seroprevalence between the two decades (83.17 and 87.80%, P = 0.023), there was no significant difference in male patients with HIV (88.76 and 87.32% in the first and second decade, respectively (P = 0.196). The cumulative HCMV prevalence of all HIV-negative patients tested in the past 20 years demonstrates a biphasic, age-related rise of HCMV seroprevalence throughout all age-groups. The seroprevalence of HCMV has declined between 1988-1997 and 1998-2008 in Frankfurt am Main, Germany. The decline varied between different age-groups. HCMV prevalence correlates with the type of health insurance, gender, age, and HIV-status.

The clinical value of neutrophil extracellular traps

Neutrophil extracellular traps (NETs) have recently been discovered as a central part of antimicrobial innate immunity. In the meanwhile, evidence accumulated that NETs are also generated upon non-infectious stimuli in various clinical settings. In acute or chronic inflammatory disorders aberrantly enhanced NET formation and/or decreased NET degradation seems to correlate with disease outcome. This review summarizes current knowledge about the relation of NETs in a broad spectrum of clinical settings. Specifically, we focus on the importance of NETs as a predictive marker in severely ill patients and further, we speculate about the potential pathophysiology of NETs.

Active cytomegalovirus infection is common in mechanically ventilated medical intensive care unit patients

OBJECTIVE

To assess the incidence, risk factors, and outcome of active cytomegalovirus (CMV) infection in nonimmunosuppressed intensive care unit (ICU) patients.

DESIGN

Prospective epidemiologic study.

SETTING

A medical ICU in a university hospital.

PATIENTS

Two hundred forty-two nonimmunosuppressed ICU patients mechanically ventilated for >or=2 days.

INTERVENTIONS

Routine pp65 antigenemia and serology for CMV were performed at admission, and then weekly. Bronchoalveolar lavage viral cultures were done when pneumonia was suspected.

MEASUREMENTS AND MAIN RESULTS

Thirty-nine of the 242 ICU patients (16.1%, confidence interval 11.5% to 20.7%) developed an active CMV infection, as diagnosed by positive antigenemia (85%) and/or positive rapid viral culture in bronchoalveolar lavage (26%). Antiviral treatment was initiated in 21 (54%) patients. ICU mortality (54% vs. 37%, p = 0.082) and in-hospital mortality (59% vs. 41%, p = 0.058) were increased in patients with active CMV infection, as compared with those without active CMV infection. Active CMV infection and Simplified Acute Physiology Score II at admission were associated with ICU death on multivariate analysis. The patients with active CMV infection had longer mechanical ventilation and longer ICU stay and were significantly more prone to developing bacterial nosocomial infections (p < 0.001). Logistic regression analysis showed that prior admission to other wards (p = 0.043; odds ratio [OR], 2.49), blood transfusions (p = 0.04; OR, 3.31), enteral feeding (p = 0.005; OR, 3.00), recent corticosteroid use before ICU admission (p = 0.08; OR, 2.26), and age (p = 0.07; OR, 1.026) were associated with the occurrence of active CMV infection.

CONCLUSIONS

: Active CMV infection is common among previously healthy patients under mechanical ventilation in a medical ICU. Further studies are needed to evaluate the role of antiviral treatments to reduce both the incidence and the outcome impact of active CMV infection.

Impaired vascular function in mice with an active cytomegalovirus infection

Human cytomegalovirus (CMV) is implicated in vascular complications through endothelial dysfunction. However, the effect of in vivo infections on vascular function in isolated arteries has not been examined. In pregnancy, systemic and uterine vascular adaptations accommodate increased blood volume through several mechanisms, including decreased sensitivity to vasoconstrictors and increased production of endothelial-dependent vasodilators. We hypothesized that an active in vivo CMV infection would reduce vasodilation of isolated arteries to the endothelial-dependent vasodilator methacholine and increase vasoconstriction to the α1-adrenergic receptor agonist phenylephrine and that these CMV-induced changes would be accentuated in late pregnancy. A mouse CMV infection model was used to study vascular responses in isolated mesenteric and uterine arteries from nonpregnant and late pregnant mice. In the mouse, CMV is not transmitted to the fetus. Accordingly, there was no evidence of active infection in any fetus examined, even though an active infection was found in salivary glands, uterine and mesenteric arteries, and placentas. Contrary to our hypothesis, increased endothelial-dependent vasodilation was found in mesenteric arteries from infected compared with uninfected nonpregnant and pregnant mice These data implicate active CMV infections in hypotensive disorders. Similarly, increased vasodilation was found in uterine arteries from infected vs. uninfected nonpregnant mice. However, this was completely reversed in infected compared with uninfected late pregnant mice in which vasodilation in uterine arteries was significantly reduced. Uterine arteries from infected pregnant mice also showed increased vasoconstriction to phenylephrine. Maternal infection led to decreased placental weights but had no effect on fetal weights in late pregnancy. These novel data demonstrate abnormal systemic and uterine vascular responses during an active CMV infection in both nonpregnant and late pregnant mice. Importantly, despite reduced placental weights, fetal weights were maintained, suggesting effective intrauterine compensation in the mouse model.