I imagine myself to have a very robust immune system because I very seldom catch a flu or cold, take Vitamins C and D, exercise, am not overweight, ran around barefoot when I was 3-4 years old, eating dirt and pill bugs outside the family house I have now moved back into 75 years later. This optimistic view is tempered quite a bit by information in Greenwoods's recent article
describing how the aging immune system begins to shift into a heightened state of alert, dialing up inflammation and running out of certain immune cells. This is because the body's first line of defense against virus infiltration, that normally also cleans up damaged cells, misfolded proteins and other detritus in the body - even in the absence of an infection - begins to be overwhelmed by increasing amount of waste, and slides into a constant state of alert and inflammation. And...
At the same time, elderly cells in tissues throughout the body are thought to change with age, releasing inflammatory substances of their own...even perfectly healthy 65-year-olds usually have higher levels of immune proteins, like cytokines, involved in inflammation than younger people do. This heightened state of chronic inflammation, sometimes called “inflammaging,” is linked to frailty — older adults with higher levels of it may be more fragile and less mobile...fighting off pathogens becomes more complicated: All of this baseline inflammatory chaos in an aging body makes it harder for the messages sent out by the innate immune system to reach their targets...there’s the added danger that the innate immune system may overreact...the aging immune system might be linked to reports of severe Covid-19 culminating in a cytokine storm, a reaction that causes high numbers of immune messengers to flood the body and can lead to organ failure...This inflammation may also be part of why vaccines, whose effectiveness relies on a robust reaction from the immune system, don’t work as well in older people — an effect that’s likely to extend to Covid-19 vaccines.
Several days after the innate immune response begins, the body begins a second wave of attacks against the viral invader. This adaptive immune system response is more targeted than the first, methodically destroying cells infected by this specific virus...in older bodies, the adaptive response not only takes longer to get into gear, it arrives to find a scene of inflammatory pandemonium...These delays mean that the pathogen has already made many copies of itself by the time the adaptive immune system gets to work and gains a foothold that might not have been available in a younger person. Additionally, older people have fewer fresh T cells, important players in the adaptive response that are trained to hunt down cells infected with a specific pathogen.
Since it became clear that the virus sometimes provokes an out-of-control immune response, researchers have been testing whether reducing inflammation might help. Drugs that tamp down the levels of cytokines, like those used for treating rheumatoid arthritis and other autoimmune diseases, have not shown success in fighting the virus. What’s more, chloroquine, which can help inhibit the aging of cells, caused increased mortality in Covid-19 clinical trials.
But the steroid dexamethasone, a potent anti-inflammatory, has been shown to reduce deaths from the virus. It resulted in one-third fewer deaths in people on ventilators and one-fifth fewer deaths in those on oxygen, according to a study published in June. (The drug may be ineffective, or even harmful, for patients in the early stages of the disease, however.)
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