Inflammation and reactivation of latent herpesviruses in older adults

Abstract

Inflammation increases with age and is associated with many chronic diseases that are prevalent among older adults. Persistent pathogens such as latent herpesviruses and chronic bacterial infections can act as a source of inflammation. Herpesviruses, including Epstein-Barr virus (EBV) and cytomegalovirus (CMV), establish latent infections following primary infection and reactivate when the cellular immune system is compromised. EBV and CMV replication can induce proinflammatory cytokine production and thus could influence systemic inflammation. The present study addressed relationships among EBV and CMV antibody titers, and levels of C-reactive protein (CRP) and interleukin-6 (IL-6) in a sample of 222 community dwelling older adults (mean(age)=64.1±14.1 years). Participants were divided into two groups based on whether they were EBV seropositive and CMV seronegative (EBV+CMV-), or EBV and CMV seropositive (EBV+CMV+). Among individuals who were EBV+CMV-, EBV antibody titers were not associated with either CRP or IL-6 levels. However, among those who were EBV+CMV+, higher EBV antibody titers were related to elevated levels of CRP and IL-6 in those individuals with higher CMV antibody titers; there was no relationship between EBV antibody titers and CRP or IL-6 levels in those participants with lower CMV antibody titers. These data suggest that the combination of latent EBV and CMV reactivation (indexed by antibody titers) may boost CRP and IL-6 production. Thus, reactivation of multiple herpesviruses may drive inflammation and could contribute to poorer health among older adults.

Figure 1. The moderating role of CMV antibody titers in the relationship between EBV antibody titers and CRP

*simple slope, b=.27, t(110)=2.02, p < .05 The regression analyses used the full range of EBV and CMV antibody titers as continuous variables. CMV antibody titers were stratified for graphical purposes using +/− 1 standard deviation from the mean. The line representing those with lower CMV antibody titers does not significantly differ from zero (simple slope, b=−.15, t(110)=−1.29, p = .20).

Figure 2. The moderating role of CMV antibody titers in the relationship between EBV antibody titers and IL-6

*simple slope, b=.13, t(110)=3.13, p < .05 The regression analyses used the full range of EBV and CMV antibody titers as continuous variables. CMV antibody titers were stratified for graphical purposes using +/− 1 standard deviation from the mean. The line representing those with lower CMV antibody titers does not significantly differ from zero (simple slope, b=.01, t(110)=.28, p = .78).