Impact of cytomegalovirus load on host response to sepsis

Cytomegalovirus durably primes neutrophil oxidative burst

Cytomegalovirus (CMV) is a ubiquitous herpes virus that infects most humans, thereafter persisting lifelong in tissues of the host. It is a known pathogen in immunosuppressed patients, but its impact on immunocompetent hosts remains less understood. Recent data have shown that CMV leaves a significant and long-lasting imprint in host immunity that may confer some protection against subsequent bacterial infection. Such innate immune activation may come at a cost, however, with potential to cause immunopathology. Neutrophils are central to many models of immunopathology, and while acute CMV infection is known to influence neutrophil biology, the impact of chronic CMV infection on neutrophil function remains unreported. Using our murine model of CMV infection and latency, we show that chronic CMV causes persistent enhancement of neutrophil oxidative burst well after resolution of acute infection. Moreover, this in vivo priming of marrow neutrophils is associated with enhanced formyl peptide receptor expression, and ultimately constitutive c-Jun N-terminal kinase phosphorylation and enhanced CD14 expression in/on circulating neutrophils. Finally, we show that neutrophil priming is dependent on viral load, suggesting that naturally infected human hosts will show variability in CMV-related neutrophil priming. Altogether, these findings represent a previously unrecognized and potentially important impact of chronic CMV infection on neutrophil responsiveness in immunocompetent hosts.

Reactivation of latent human cytomegaloviral infection in critically ill patients

Background & objectives

Human cytomegalovirus (HCMV) is a frequent participant in the infectious process in critically ill patients. This study aimed to determine the incidence of HCMV reactivation in critically ill patients and estimate the clinical effect of reactivation on the course of the pathological process.

Methods

To determine the incidence of HCMV reactivation, plasma and sputum samples were collected from 82 critically ill patients. HCMV reactivation was determined by quantitative PCR together with the presence of circulating HCMV IgG in the plasma. The statistical analysis of clinical data employed methods of descriptive (median with 95% confidence interval; minimum and maximum values, interquartile range) and nonparametric statistics [Mann-Whitney U test, odds ratio (OR), Kaplan-Meier survival analysis].

Results

HCMV reactivation was found in 36.6 per cent of cases. An association between the presence of sepsis and the development of HCMV reactivation (P<0.001), as well as higher HCMV viral loads in septic patients, was found. There was also an association between the presence of HCMV DNA and the subsequent development of sepsis (OR=1.504). The involvement of HCMV in the emerging immunological shifts manifested by a decrease in CD8+ T-lymphocytes (P=0.01) and an increase in the immunoregulatory index (P=0.03) was found.

Interpretation & conclusions

HCMV reactivation can influence the course of bacterial pathology with a deteriorating effect on such groups of patients. Monitoring the viral load of latent HCMV can be helpful in the assessment of the host immune status, the course of the pathological process, and its clinical prognosis.

Effect of Cytomegalovirus Infection on the Central Nervous System: Implications for Psychiatric Disorders

Cytomegalovirus (CMV) is a common herpesvirus that establishes lifelong latent infections and interacts extensively with the host immune system, potentially contributing to immune activation and inflammation. Given its proclivity for infecting the brain and its reactivation by inflammatory stimuli, CMV is well known for causing central nervous system complications in the immune-naïve (e.g., in utero) and in the immunocompromised (e.g., in neonates, individuals receiving transplants or cancer chemotherapy, or people living with HIV). However, its potentially pathogenic role in diseases that are characterized by more subtle immune dysregulation and inflammation such as psychiatric disorders is still a matter of debate. In this chapter, we briefly summarize the pathogenic role of CMV in immune-naïve and immunocompromised populations and then review the evidence (i.e., epidemiological studies, serological studies, postmortem studies, and recent neuroimaging studies) for a link between CMV infection and psychiatric disorders with a focus on mood disorders and schizophrenia. Finally, we discuss the potential mechanisms through which CMV may cause CNS dysfunction in the context of mental disorders and conclude with a summary of the current state of play as well as potential future research directions in this area.

Cytomegalovirus reactivation in immunocompetent mechanical ventilation patients: a prospective observational study

BACKGROUND

Cytomegalovirus (CMV) reactivation is associated with adverse prognoses of critically ill patients. However, the epidemiology and predictors of CMV reactivation in immunocompetent patients receiving mechanical ventilation (MV) are not clear. The aim of this study was to investigate the epidemiology and predictors of CMV reactivation in immunocompetent patients requiring MV.

METHODS

A single-center, prospective observational study (conducted from June 30, 2017 to July 01, 2018) with a follow-up of 90 days (September 29, 2018) that included 71 CMV-seropositive immunocompetent patients with MV at a 37-bed university hospital general intensive care unit (ICU) in China. Routine detection of CMV DNAemia was performed once a week for 28 days (Days 1, 7, 14, 21, and 28). CMV serology, laboratory findings, and clinical data were obtained during hospitalization.

RESULTS

Among 71 patients, 13 (18.3%) showed CMV reactivation within 28 days in the ICU. The median time to reactivation was 7 days. CMV reactivation was related to various factors, including body mass index (BMI), sepsis, N-terminal pro-b-type natriuretic peptide (NT-proBNP), blood urea nitrogen (BUN), and hemoglobin (Hb) levels (P < 0.05). In the multivariate regression model, BMI, Hb level, and sepsis were independently associated with CMV reactivation patients (P < 0.05). Moreover, the area under the receiver operating characteristic (AUROC) of BMI, Hb, and BMI combined with Hb was 0.69, 0.70, and 0.76, respectively. The duration of MV, hospitalization expense, length of ICU stay, and 90 day all-cause mortality rate in patients with CMV reactivation was significantly higher than in those without CMV reactivation (P < 0.05).

CONCLUSIONS

Among immunocompetent patients with MV, the incidence of CMV reactivation was 18.3%. CMV reactivation was associated with several adverse prognoses. BMI, Hb, and sepsis were independent risk factors for CMV reactivation. BMI and Hb may predict CMV reactivation.

Respiratory viral sepsis: epidemiology, pathophysiology, diagnosis and treatment

According to the Third International Consensus Definition for Sepsis and Septic Shock, sepsis is a life-threatening organ dysfunction resulting from dysregulated host responses to infection. Epidemiological data about sepsis from the 2017 Global Burden of Diseases, Injuries and Risk Factor Study showed that the global burden of sepsis was greater than previously estimated. Bacteria have been shown to be the predominant pathogen of sepsis among patients with pathogens detected, while sepsis caused by viruses is underdiagnosed worldwide. The coronavirus disease that emerged in 2019 in China and now in many other countries has brought viral sepsis back into the vision of physicians and researchers worldwide. Although the current understanding of the pathophysiology of sepsis has improved, the differences between viral and bacterial sepsis at the level of pathophysiology are not well understood. Diagnosis methods that can broadly differentiate between bacterial and viral sepsis at the initial stage after the development of sepsis are limited. New treatments that can be applied at clinics for sepsis are scarce and this situation is not consistent with the growing understanding of pathophysiology. This review aims to give a brief summary of current knowledge of the epidemiology, pathophysiology, diagnosis and treatment of viral sepsis.

Pediatric roots of cytomegalovirus recurrence and memory inflation in the elderly

The establishment of a lifelong latent infection after resolution of primary infection is a hallmark of cytomegalovirus (CMV) biology. Primary infection with human CMV is possible any time in life, but most frequently, virus transmission occurs already perinatally or in early childhood. Many years or even decades later, severe clinical problems can result from recurrence of infectious virus by reactivation from latency in individuals who undergo immunocompromising medical treatment, for instance, transplant recipients, but also in septic patients without canonical immunosuppression, and in elderly people with a weakened immune system. The diversity of disease manifestations, such as retinitis, pneumonia, hepatitis, gastrointestinal disease, and others, has remained an enigma. In clinical routine, seropositivity for IgG antibodies against human CMV is taken to indicate latent infection and thus to define a qualitative risk of recurrence, but it is insufficient as a predictor for the quantitative risk of recurrence. Early experimental studies in the mouse model, comparing primary infection of neonatal and adult mice, led to the hypothesis that high load of latent viral genomes is a better predictor for the quantitative risk. A prolonged period of virus multiplication in the immunologically immature neonatally infected host increased the risk of virus recurrence by an enhanced copy number of latent virus genomes from which reactivation can initiate. In extension of this hypothesis, one would predict today that a higher incidence of reactivation events will also fuel the expansion of virus-specific T cells observed in the elderly, a phenomenon known as "memory inflation". Notably, the mouse model also indicated a stochastic nature of reactivation, thus offering an explanation for the diversity and organ selectivity of disease manifestations observed in patients. As the infection history is mostly undefined in humans, such predictions from the mouse model are difficult to verify by clinical investigation, and moreover, such questions were actually rarely addressed. Here, we have surveyed the existing literature for reports that may help to retrospectively relate the individual infection history to the risk of virus recurrence and recrudescent organ disease.