Hip
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Chronic Infections And Nitric Oxide (NO) Levels
I have often wondered whether the chronic infections of ME/CFS might lead to low NO levels, high NO levels, or a combination of both (some bodily areas low in NO, others high in NO).
Nitric oxide is used for three distinct purposes in the body:
• For vasodilation (NO dilates blood vessels)
• For neurotransmission (NO is an important neurotransmitter)
• By the immune system for antimicrobial purposes (NO is a potent antiviral, antibacterial, antifungal and antiprotozoal).
Corresponding to these three functions, there are three enzymes in the body that produce nitric oxide: eNOS (in the endothelium for vasodilation), nNOS (in the brain for neurotransmission), and iNOS (created anywhere in the body for immune purposes).
The immune system makes NO for its potent antimicrobial effects. Interestingly, the amount of NO produced by the immune system via the iNOS enzyme is hundreds or thousands of times higher than the levels of NO produced by eNOS and nNOS for vasodilation and neurotransmission purposes. When the immune system makes NO, it makes it in bucketloads; whereas the NO used for vasodilation and neurotransmission is only made in relatively tiny amounts.
So I wonder whether these bucketloads of NO from the immune system might actually be disturbing the dynamics of the tiny amounts of NO used for vasodilation and neurotransmission. If there were disturbances in the NO levels employed for vasodilation and neurotransmission, this might help explain the reduced cerebral blood flow sometimes found in ME/CFS, and might help explain the mental and cognitive symptoms of ME/CFS (as a neurotransmitter, NO is associated with learning and memory, so might be behind brain fog).
The disturbance to NO in vasodilation and neurotransmission could simply result from the very high amounts of NO produced by the immune system as it combats a chronic local infection (of the brain for example). With the immune system producing NO at levels hundreds or thousand of times higher than the NO manufactured for vasodilation and neurotransmission, this immune-derived NO might entirely swamp the vasodilation-derived and neurotransmission-derived NO.
Furthermore, there may be paradoxical effects of the high levels of immune-derived NO, that actually lead to lowered NO levels in other parts of the body.
For example, if we consider asymmetric dimethylarginine (ADMA), which is an inhibitor of the nitric oxide synthase (NOS) enzymes and is intimately involved with NO metabolism, we find in chronic infections, ADMA can be raised.
This paper mentions that in HIV-infected patients there are elevated plasma levels of ADMA. And in Helicobacter pylori infection you also find increases in ADMA levels; see here.
So some chronic infections seem to increase blood levels of ADMA. And since ADMA inhibits all three of the NOS enzymes, high levels of ADMA due to infection might alter the dynamics of eNOS and nNOS vasodilation and neurotransmission.
Or if, as @aimossy mentioned above, we consider Mady Hornig's results of significantly reduced ADMA in the first 3 years of ME/CFS, this might also alter the dynamics of eNOS and nNOS vasodilation and neurotransmission.
I have often wondered whether the chronic infections of ME/CFS might lead to low NO levels, high NO levels, or a combination of both (some bodily areas low in NO, others high in NO).
Nitric oxide is used for three distinct purposes in the body:
• For vasodilation (NO dilates blood vessels)
• For neurotransmission (NO is an important neurotransmitter)
• By the immune system for antimicrobial purposes (NO is a potent antiviral, antibacterial, antifungal and antiprotozoal).
Corresponding to these three functions, there are three enzymes in the body that produce nitric oxide: eNOS (in the endothelium for vasodilation), nNOS (in the brain for neurotransmission), and iNOS (created anywhere in the body for immune purposes).
The immune system makes NO for its potent antimicrobial effects. Interestingly, the amount of NO produced by the immune system via the iNOS enzyme is hundreds or thousands of times higher than the levels of NO produced by eNOS and nNOS for vasodilation and neurotransmission purposes. When the immune system makes NO, it makes it in bucketloads; whereas the NO used for vasodilation and neurotransmission is only made in relatively tiny amounts.
So I wonder whether these bucketloads of NO from the immune system might actually be disturbing the dynamics of the tiny amounts of NO used for vasodilation and neurotransmission. If there were disturbances in the NO levels employed for vasodilation and neurotransmission, this might help explain the reduced cerebral blood flow sometimes found in ME/CFS, and might help explain the mental and cognitive symptoms of ME/CFS (as a neurotransmitter, NO is associated with learning and memory, so might be behind brain fog).
The disturbance to NO in vasodilation and neurotransmission could simply result from the very high amounts of NO produced by the immune system as it combats a chronic local infection (of the brain for example). With the immune system producing NO at levels hundreds or thousand of times higher than the NO manufactured for vasodilation and neurotransmission, this immune-derived NO might entirely swamp the vasodilation-derived and neurotransmission-derived NO.
Furthermore, there may be paradoxical effects of the high levels of immune-derived NO, that actually lead to lowered NO levels in other parts of the body.
For example, if we consider asymmetric dimethylarginine (ADMA), which is an inhibitor of the nitric oxide synthase (NOS) enzymes and is intimately involved with NO metabolism, we find in chronic infections, ADMA can be raised.
This paper mentions that in HIV-infected patients there are elevated plasma levels of ADMA. And in Helicobacter pylori infection you also find increases in ADMA levels; see here.
So some chronic infections seem to increase blood levels of ADMA. And since ADMA inhibits all three of the NOS enzymes, high levels of ADMA due to infection might alter the dynamics of eNOS and nNOS vasodilation and neurotransmission.
Or if, as @aimossy mentioned above, we consider Mady Hornig's results of significantly reduced ADMA in the first 3 years of ME/CFS, this might also alter the dynamics of eNOS and nNOS vasodilation and neurotransmission.