Acute inflammation happens as a part of our defense mechanism to clear out pathogens. So when a virus or bacteria invades us, we need to quickly mount an acute inflammatory response to get rid of the pathogen. Sometimes, that acute immune response isn’t enough to get rid of the pathogen. That’s when we elevate the level to the adaptive immune response. That’s when you involve specific lymphocytes, T and B cells, to fight off the infection.
So inflammation is a necessary process for dealing with pathogens but sometimes, it can also turn against us. Chronic inflammation happens because the body fails to get rid of the cause of the inflammation, such as viruses and bacteria. In those conditions, such as, you know, chronic infection with HIV or hepatitis virus or lung COVID, in which case we there may be a persistent viral reservoir that’s causing this chronic inflammation, the inflammation itself becomes the enemy.
Even though inflammation evolve to counter pathogens, it’s also engaged by other causes, and so having this amount of fat, for example, alone is able to trigger the immune system and induce the chronic inflammatory response that then fuels further problems to happen because the body is sort of trying to fight off a non-existent infection and therefore, it can sort of engage a chronic state of inflammation.
I can’t think of a disease which doesn’t involve inflammation, but we are now learning more and more about the physiological role of inflammation. Homeostasis ensures that we have a normal operation of different physiological functions like heart rate, breathing and glucose levels or insulin levels. Those two system, the inflammatory system and the homeostasis, they work together to maintain each other. Sometimes, the inflammatory response has to override the homeostatic response.
That includes things like adaptation to a different diet. The immune cells are now known to be able to sense differences in dietary conditions and adapt the intestine for future absorption of nutrients. This kind of events that are not necessarily at all related to pathogens, but for maintaining physiology. Inflammatory responses are integral in order to maintain health. So a molecular-level understanding of inflammation is necessary to understand the logic by which these systems function, and also it provides the pharmaceutical target for future therapies of inflammatory diseases.