Transcriptional Activity of Human Endogenous Retroviruses in Human Peripheral Blood Mononuclear Cells

Abstract

Human endogenous retroviruses (HERVs) have been implicated in human physiology and in human pathology. A better knowledge of the retroviral transcriptional activity in the general population and during the life span would greatly help the debate on its pathologic potential. The transcriptional activity of four HERV families (H, K, W, and E) was assessed, by qualitative and quantitative PCR, in PBMCs from 261 individuals aged from 1 to 80 years. Our results show that HERV-H, HERV-K, and HERV-W, but not HERV-E, are transcriptionally active in the test population already in the early childhood. In addition, the transcriptional levels of HERV-H, HERV-K, and HERV-W change significantly during the life span, albeit with distinct patterns. Our results, reinforce the hypothesis of a physiological correlation between HERVs activity and the different stages of life in humans. Studies aiming at identifying the factors, which are responsible for these changes during the individual's life, are still needed. Although the observed phenomena are presumably subjected to great variability, the basal transcriptional activity of each individual, also depending on the different ages of life, must be carefully considered in all the studies involving HERVs as causative agents of disease.

The involvement of human endogenous retroviruses K (HERV-K) in aging processes via induction of inflammation

“…Since the end of a reproductive period, decreasing level of sex hormones opens a way to chronic inflammation and launches the positive-feedback loop mechanism between HERVs and proinflammatory factors. This conclusion is consistent with a data about significant changes with distinct patterns in the transcriptional levels of HERV-H, HERV-K, and HERV-W during the lifespan (Balestrieri et al, 2015). Median transcription level of HERV-K in childhood is negligible but dramatically boosts during puberty.…”

“…The HERV-K transcription activity decreases in young adults, but then constantly rises with age. The HERV-W activity drops in young adults and surges in the middleaged and slightly decreases in the elderly people (Balestrieri et al, 2015).…”

An analysis of the mechanism of aging: endogenous viral stimulus and the deleterious effect of chronic inflammation

“…Endogenous retroviruses are able to harm organism mostly through activation of innate immune response and then promoting chronic inflammation. It is demonstrated by the dynamics of the transcriptional levels of HERVs during the lifespan (Balestrieri et al, 2015). Median transcription level of HERV-K in childhood is negligible but dramatically elevates during puberty.…”

“…The HERV-K transcription activity slightly decreases in young adults, but then constantly rises with age. The HERV-W activity drops in young adults and drastically surges in the middle-aged and slightly decreases in the elderly people (Balestrieri et al, 2015). Ageassociated changes in the activity of HERVs explains why individual development is linked to aging processes because growth retardation and late maturation lead to increased lifespan prompting an idea of the developmental origin of aging (de Magalhães, 2012).…”

Human Endogenous Retrovirus: Their Relationship with Hematological Diseases

“…Provided that the integration process and replication of the inserted virus does not prevent fertilization, the fetus will then carry the retroviral element in all its somatic and germ-line cells, thus, the provirus becomes part of the human genome and it is transmitted to the following generations. To date, approximately 8% of the human genome is composed of such retroviral sequences [4,5].…”