Wednesday, July 11, 2018
Wisdom Wednesday: Lifelong CMV Infection Improves Immune Defense in Old Mice
Epidemiological studies have shown a correlation between CMV infection and immune system aging, especially in elderly populations. It remains unclear whether CMV infection is a key driver of, or simply a factor associated with, aging of the immune system. In this study, we show that CMV infection improves T cell immunity in old animals by broadening the immune response to a different pathogen. Animals that have aged with CMV are able to recruit novel T cells into these immune responses that are present in, but not utilized in, animals aging without CMV. This data squarely challenges the premise that CMV is solely detrimental to the aging of the adaptive immune system.
The abstract was very technical so I didn’t repeat it here. However, these researchers basically exposed old mice with a history of CMV and a control group to Listeria monocytogenes then looked at the immune response. They postulate that we share coevolution with CMV that may include potentially positive impacts on adaptive heterologous immunity in late life.
In younger patient populations, CMV and EBV (Epstein - Barr virus) are documented factors in at least a third of all autoimmune cases. So this study showing an immune stimulation by CMV in older patients is not surprising.
In immune compromised patients, like HIV/AIDS, CMV can cause life threatening disease.
The real question is CMV a positive or negative factor in health? In my opinion, it has the potential for both. If your immune system is balanced, then CMV probably plays a positive role. However, if your immune system is compromised or overstimulated (autoimmune disease) then the effects are negative.
As we age, our immune systems tend to decline, so the immune stimulation from a chronic CMV infection may very well provide a boost to immune function. Again, as long as the immune system is healthy to begin with.
Clinically, I frequently find an active reflex for CMV. Approximately 60% of the population carries the infection. However, I rarely find a patient that requires treatment for CMV. EBV is much more problematic, especially in MS and less often in other autoimmune disease.
Environmental toxins, most commonly Round Up and DDT, are co-factors in impairing the immune system. They appear to facilitate reservoirs of infection in various organ systems. For example, it has been theorized that DDT unbinds copper and zinc in the nervous system which allows Lyme disease to stimulate the beta-amyloid plaque clusters of Alzheimer’s disease.
While we may have coevolved with CMV, environmental toxins are a very recent addition to the genetic mix. I don’t think we will fare any better than the planet in adapting to the presence of these chemicals in our body.
The Bottom Line:
Certainly CMV is a factor in our immune system and maybe beneficial for some as we age. However, we must learn to modulate our immune system rather than inhibit or stimulate this complex, evolving chemical process of human function.
Source: July 2, 2018 PNAS