5 ms·

Can someone please explain what 'inflammation' means IRL. All kinds of studies linked to from all sorts of health obsessed forums online would have me believe

Can someone please explain what 'inflammation' means IRL. All kinds of studies linked to from all sorts of health obsessed forums online would have me believe basically everything causes 'inflammation'. Meanwhile I'm here, living my life, eating all kinds of foods, without feeling at all 'inflamed'.

dtawfik1 9y ago
Basically you produce an immune response. The immune cells that protect you when you get a cut for example have a same reaction to ingesting these types of foods.
- throw132890123 9y ago
  And this happens to who? Does it hurt? Why should I care? I know literally no-one that has ever complained about 'inflammation'. When I say explain what it means IRL, I mean please explain the impact.
  - dtawfik1 9y ago
    Well, imagine inflammation in your circulatory system. So imagine that there's this partical in your blood stream that your immune system responds to. If you have too many inflammatory responses you could get a blockage. That blockage could lead to a heart attack. That's one example but these inflammatory responses are also linked to a bunch of diseases. I hope that is a helpful answer.
    - dtawfik1 9y ago
      https://www.mc.vanderbilt.edu/vanderbiltmedicine/the-good-the-bad-and-the-ugly-of-inflammation/ https://www.mc.vanderbilt.edu/vanderbiltmedicine/the-good-th...
      - dtawfik1 9y ago
        Here's an article the consequences of inflammation on the brain. http://www.dana.org/Publications/ReportOnProgress/Consequences_of_the_Inflamed_Brain/ http://www.dana.org/Publications/ReportOnProgress/Consequenc...
    - throw132890123 9y ago
      Not really, you're now linking the 'inflammation' described in this article to heart attacks. Surely that'd be a bigger story? From the 'article' you linked to: > Obesity and its constant companion, type 2 diabetes, are at epidemic proportions in this country. One thing that connects them is inflammation. How is this not a most blatant case of 'correlation vs causation'? We know the causes of obesity AND type 2 diabetes. Surely inflammation, a cellular immune thing ... is just a correlating factor?
      - dtawfik1 9y ago
        https://www.uaf.edu/files/olli/OLLI_15_chol_4_red.pdf https://www.uaf.edu/files/olli/OLLI_15_chol_4_red.pdf Checkout slides 7 and 8. My simple understanding is that the sugar creates a particle that provokes an immune response. Cytokines attack the sugar-lipid particle that has been oxidized.
        subcosmos 9y ago
        Glucose, in high concentration, reacts with proteins at arbitrary locations, effectively gluing them together. This is bad, so the immune system detects this (with a receptor called RAGE) and sends in reinforcements to eat the mess up. https://en.wikipedia.org/wiki/RAGE_(receptor) https://en.wikipedia.org/wiki/RAGE_(receptor)
      - subcosmos 9y ago
        There's compelling evidence that inflammation can cause insulin resistance and fat accumulation, and that insulin resistance and fat accumulation can further cause inflammation. We've found signaling pathways in the body that connect in both directions. So yeah, the causality is actually circular, which in the context of human health implies that a snowball effect is in fact occurring. Escaping this feedback loop is the hard part that we are still working on in the lab.
  - thephyber 9y ago
    Not a medical professional, but... Athletes feel aches and pain from inflammation of their muscles. Old persons frequently have inflammation in their joints which causes pain and stiffness. Asthma sufferers have inflammation in their lungs. Anyone (except hemophiliacs) who receives a skin cut has inflammation at the site of the cut. It's an immune response and is a level of abstraction away from the actual observable symptoms, hence the general confusion about what it is.
    - throw132890123 9y ago
      Right I've heard of those examples, but they have nothing to do with diet. So when people say 'eating sugar causes inflammation' what do they mean? How is THAT inflammation felt?
      - dragonwriter 9y ago
        > Right I've heard of those examples, but they have nothing to do with diet. They do, in fact; a pro-inflammatory diet makes the threshold at which symptoms are felt from any of those other source lower, because inflammation has a substantial systemic component. (It may produce unique symptoms of its own, too, but I think the main dietary concern with inflammation is systemic contribution to lowering thresholds to inflammatory symptoms when other triggers are present.)
      - subcosmos 9y ago
        Bad diet causes brain inflammation. You don't feel pain in this case, but you feel tired and hungry, because the part of the brain getting inflamed specifically regulates metabolism and appetite. We know there is inflammation there because the brains immune system goes apeshit, and we can see this under the microscope. Gliosis is the technical name.
      - tqkxzugoaupvwqr 9y ago
        From my own experience, when I eat too much food that contains high amounts of sugar, I start feeling like I’m getting a cold. I get a sore throat, feel much less energetic, like my body is fighting a disease, skin on my head starts itching and turns red, my nose starts shedding. The symptoms get worse when I keep eating high amounts of sugar. When I feel an onset, I avoid sugar to starve the inflammation. High amounts of sugar that trigger the symptoms means >100g in 24 h or >60g per day over several days. The effect also depends on the food, probably because of how it is digested. Sugary water (fruit juice, soda) is worse than solid meals. Some forms of sugar are worse than others, e.g. I can eat some chocolate in moderation but others (e.g. Milka) I get a soar throat within minutes of eating a single piece (<10g).
  - ChuckMcM 9y ago
    It is the new "bad" thing and thus gets a lot of press lately but it is also probably true that you have hear many complaints, you just may not have associated them. A sore throat, is caused by inflammation of the mucus tissues in your throat, for example. A mosquito bite itches due to inflammation, it is the immune response to the mosquito's saliva that you feel as an itching sensation. The 'new' thing however is that this mechanism can occur pretty much in every cell of your body and some people have speculated it is the root of a number of ailments. Google 'inflammation' on scholar.google.com and you will find a number of papers discussing different ways that it can affect you.
    - throw132890123 9y ago
      > Google 'inflammation' on scholar.google.com and you will find a number of papers discussing different ways that it can affect you. No thanks, I'm specifically asking for an explanation of how it affects me.
      - ChuckMcM 9y ago
        Mail me a blood sample. :-) More seriously, your question, as stated, can only be answered by your doctor and then probably only after taking various samples. What is worse is that inflammation is typically a response to something else, so it is at least a second order symptom rather than a primary cause. (for example your sore throat is from inflammation, but the inflammation is from a response to something the mucus membrane didn't like. Could be a cold, it could be the chlorine you drank.) Symptoms associated with inflammation are aches, pain, vomiting, diarrhea, fainting, swelling, and itching at least. If you have any of those symptoms, it is affecting you.
      - subcosmos 9y ago
        What YOU (sometimes) feel is pain, redness, and swelling. What your cells feel, are signals from your immune system (cops) to "freeze and stop doing shit". This message is delivered in the form of cytokines. What happens inside the cell, is metabolism slows, and recycling begins. Too much of this leads to atrophy. At the organ level, this causes various diseases of aging. Muscle wasting. Brain atrophy. Liver disease (alcoholic or dietary).
maxxxxx 9y ago
If you are like me then sugar will give you joint pain, headaches and sometimes fever like symptoms. Very noticeable. I wouldn't generalize this though. What has a negative impact on me can be perfectly fine for you.
- criddell 9y ago
  You know - I've just noticed this myself. If I eat a lot of sugary foods, I often almost feel hungover the next day.
  - maxxxxx 9y ago
    I really noticed this only when I stayed at a Yoga Ashram for a month. After two weeks of eating only rice, lentils and vegetables all the little aches I was used to have were gone. I had had no idea how good I could actually feel.
delhanty 9y ago
I don't understand what it means either. But one thing I've picked up is that inflammation isn't all bad - in fact some of it is necessary, particularly for growth. Obviously, as you get older growth becomes less necessary, and cancers very much like to grow too ... so there is a trade off going on and the balance shifts so that inflammation is less desirable as we age. A couple of good inflammation for growth examples: Wound healing has an inflammatory phase. [0] "There is a known relationship between inflammation and muscle growth.For instance, high doses of anti-inflammatory medicines (e.g., NSAIDs) are able to blunt muscle growth." [1] [0] https://en.wikipedia.org/wiki/Wound_healing#Inflammatory_phase https://en.wikipedia.org/wiki/Wound_healing#Inflammatory_pha... [1] https://en.wikipedia.org/wiki/Inflammation#Post-inflammatory_muscle_growth_and_repair https://en.wikipedia.org/wiki/Inflammation#Post-inflammatory...
randomstudent 9y ago
This is a very important question, which I'll try to answer as clearly as possible. First, a word of warning: This doesn't look like the appropriate kind of article to be posted on HN. As a doctor, it's hard to understand all that's going on, and even harder to appreciate what the real impact of this research is. Laymen should completely ignore this kind of articles, and read instead clinical trials or meta-analysis that report practical outcomes people are actually interested in, like life expectancy, cure rates, exercise capacity, weight loss, etc. This paper is about some molecular mumbo-jumbo that is not very interesting in itself, unless you're a researcher in the area. Now, to answer the question. Classically, inflammation was defined by Celsus and Galen as 5 cardinal signs (in latin): - Tumor (swelling) - Calor (warmth) - Rubor (redness - more noticeable in light skin; don't forget that Celsus and Galen worked primarily with patients from Europe and the Middle East) - Dolor (pain) - Functio laesa (loss of function) These are clinical signs, that is, something the doctor can observe at the bedside. Think of when you fall and hurt your knee: the area where the impact happens swells. It might become warm to the touch. The skin might become red (different from bleeding). You'll feel pain, and for a while, your knee won't work very well because it hurts (loss of function). You don't need any fancy equipment to analyse these signs. Now, these are adaptations of the body to injury: redness and warmth appear because the blood vessels in the skin dilate in response to injury. Blood brings red blood cells, which caus redness, and heat from the inside of the body, which causes the skin to be warm to the touch. The blood vessels also "open holes", which causes the liquid part of the blood to escape the bloo vessels and get between the cells, thus causing swelling. The injured cells release signalling substances, which are detected by neurons in the skin, thus causing the individual to feel pain. Finally, some or all of these changes, might cause the limb to lose it's usefullness (because it hurts and it's swollen). The goal of inflammation is to bring white blood cells to the place of the injury in order to fight a possible infection and assist in the repair of the injured tissue. Pain doesn't help protect or repair the tissue directly, but it notifies the organism to the fact that something wrong is happening, which causes the brain to act appropriately: remove the limb from a hot surface in the case of a burn, protect a wound, etc. People that are not sensitive to pain have serious problems from childhood because they lack these indirect protective responses (they won't remove their hand from burning coals, even as they smell their flesh burning, for example) This is the classical picture of inflammation, caused by a wound or trauma to the body. It's simple, and it's functions are (nowadays) obvious. But we can go deeper... Let's talk about pneumonia. Pneumonia happens when a bacteria or virus overwhelms the defenses of the lungs, and starts reproducing in the normally microorganism-free lung. This causes blood vessesls to upen up (thus causing swelling), to dilate (thus causing redness), but the lung probably doesn't get any warmer - it's already pretty warm. The patient will not feel pain. After all, the inside of the lung doesn't have nerves capable of feeling pain! (the outside does, and if the inflammation gets near the peripheral part of the lung, it might be VERY painful). Maybe the lung won't get any warmer (it's already pretty warm already). You will run a fever, but that's not the same kind of warmth we've discussed. You will feel breathlessnes, that is, loss of function of the lung. So, while some things are common the picture gets murky. Also, the body is working very hard to defend itself, and is now producing lots of molecules that circulate in the blood and which we associate with "inflammation". We now need some fancy equipement to detect these molecules: our 5 senses are not good enough. Even though the swelling if the lungs can be detected by auscultation (with a stethoscope), the doctor probably use somethin like an X-Ray machine to visualize the swelling. Let's go deeper. Some bacteria enter the bloodstreem and latch to a valve of the heart. This kind of infection is called an endocarditis. The valve has no blood vessels, so you won't get swelling. You won't get redness or warmth either (again, you ill run a fever, but that's different). The valve also has no nerve endings, so you will feel no pain! The bacteria will happily eat your valve away (and when it's eaten away you'll die), but it may take time, and meanwhile, the valve can work relatively well. So, no loss of function. Yet, your body is fighting in overdrive to clear the infection and kill the bacteria. In fact, lots of mollecules associated with inflammation are running wild all through the body, sometimes causing as much damage as the infection itself! These are the same mollecules your body produces in pneumonia, and also in other kinds of "deep" infections. So, in a sense, even though we have amost none of the 5 classical signs of inflammation, we have a response of the body that aims to defend it against infection. So we might decide to call it inflammation. Again, we can't see the inflammation here. We need some fancy machines to see the damaged valve (even though we can listen to the valve failing with a stethoscope), and fancy lab equipment to detect these molecules, as well as the consequences of the inflammation inside the body. If we go even deeper, we'll "discover" that heart attacks (technically "myocardial infarctions") are the result of inflammation too. Even though what the patient feels is just pain, possibly followed by loss of function: breathlessness and death. So, at each step, we get further removed from the intuitive description of inflammation, which you can feel with your hands and see with your eyes, into a scary realm only accessible with the help of lab equipement and thick books. At this point, inflammation is actually a buzzword that means little... This paper's conclusion doesn't mean that the hypothalamus (a part of the brain) is red, swollen, warm, painful or has stopped functioning. That would be an encephalitis, an extremely serious disease that will land you in a hospital or a coffin (see the movie "Contagion" for some realistic depictions of encephalitis). It means that some cells, vaguely associated with inflammation, are producing some mollecules which in most parts of the body are associated with inflammation. In most situations, inflammation is either bad or signals something bad. In this situation it certainly seems bad: the concrete changes that inflammation brings to the brain seems to be similar to the ones caused by diabetes (according to my cursory reading of the article). But I agree that the word has been used for so many things, that you can't actually tell whether inflammation is good or bad. On the other hand, inflammation is a defense mechanism of the body. So what is a person with no inflammation at all? It's a person really close to death, because Nature is scary and full of bugs, and someone incapable to mount an inflammatory response is what bacteria, viruses and fungi call dinner. People like these exist (either from birth or due to unfortunate circumstances), and we can only keep them alive by keeping them in very clean rooms and pumping them full of antibiotics until their immune system (and the capability to mount an inflammtory response) recovers. Using the same word for what protects us from infection and for what turns our brains into something similar to the brains of a person with untreated diabetes is confusing. We're at a point where when a doctor talks about inflammation, it has a dompletely different thing in mind from laymen. A doctor might even have something completely ifferent in mind from another doctor or from a researcher (which is more serious). In the end, I have nothing to tell you except that you're right to be confused, and if it serves as a consolation, I'm often similarly confused when I read the titles of these papers (and sometimes the abstracts), even though I've been studying these things for years.
cgh 9y ago
In the context of this study, inflammation of the hypothalamus can lead to various diseases, including metabolic syndrome and cardiovascular disease. Metabolic syndrome in particular is interesting because it's a cluster of symptoms that includes high blood sugar and obesity. It's long been known that low-carb/ketogenic diets are an effective treatment for it. You wouldn't actually feel hypothalamic inflammation. You'd eventually just get fat and ill.
- pella 9y ago
  > It's long been known that low-carb/ketogenic diets are an effective treatment for it. maybe related: cell: "Ketogenic Diet Reduces Midlife Mortality and Improves Memory in Aging Mice" ( 5 September 2017 ) http://www.cell.com/cell-metabolism/fulltext/S1550-4131(17)30489-8 http://www.cell.com/cell-metabolism/fulltext/S1550-4131(17)3... BHB == ketone body beta-hydroxybutyrate "These signaling functions suggest that BHB might itself regulate inflammation and gene expression, with implications for health and longevity. Aberrant inflammasome activity is associated with a variety of age-related diseases (Goldberg and Dixit, 2015), while moderate inhibition of histone deacetylases is associated with enhanced longevity in invertebrates (Woods and Rogina, 2016) as well as amelioration of cognitive decline (Penney and Tsai, 2014) and cardiac dysfunction (Morales et al., 2016) in mice."
pygy_ 9y ago
Inflamation is the response of the immune system to chemical signals sent by the cells of damaged tissue. Depending on the affected organ, the consequences are different. However, the mechanism at the cellular level is mostly identical. Inflamed tissue releases messengers in the blood stream that can be detected (e.g. CRP, orosomucoid, etc...). The process is generally beneficial (helps fight a threat) but it can be triggered by false positives, and the activation of the immune system can dammage healthy tissue. Too much inflammation as a reaction to a real threat can also be problematic, hence the various anti-inflamatory treatments (NSAID/corticosteroids). In this case, prossibly nocive inflammation was discovered in the hypothalamus, the part of the brain that regulates appetite among many other vegetative functions.

dtawfik1 9y ago

Basically you produce an immune response. The immune cells that protect you when you get a cut for example have a same reaction to ingesting these types of foods.

throw132890123 9y ago
And this happens to who? Does it hurt? Why should I care? I know literally no-one that has ever complained about 'inflammation'. When I say explain what it means IRL, I mean please explain the impact.
- dtawfik1 9y ago
  Well, imagine inflammation in your circulatory system. So imagine that there's this partical in your blood stream that your immune system responds to. If you have too many inflammatory responses you could get a blockage. That blockage could lead to a heart attack. That's one example but these inflammatory responses are also linked to a bunch of diseases. I hope that is a helpful answer.
  - dtawfik1 9y ago
    https://www.mc.vanderbilt.edu/vanderbiltmedicine/the-good-the-bad-and-the-ugly-of-inflammation/ https://www.mc.vanderbilt.edu/vanderbiltmedicine/the-good-th...
    - dtawfik1 9y ago
      Here's an article the consequences of inflammation on the brain. http://www.dana.org/Publications/ReportOnProgress/Consequences_of_the_Inflamed_Brain/ http://www.dana.org/Publications/ReportOnProgress/Consequenc...
  - throw132890123 9y ago
    Not really, you're now linking the 'inflammation' described in this article to heart attacks. Surely that'd be a bigger story? From the 'article' you linked to: > Obesity and its constant companion, type 2 diabetes, are at epidemic proportions in this country. One thing that connects them is inflammation. How is this not a most blatant case of 'correlation vs causation'? We know the causes of obesity AND type 2 diabetes. Surely inflammation, a cellular immune thing ... is just a correlating factor?
    - dtawfik1 9y ago
      https://www.uaf.edu/files/olli/OLLI_15_chol_4_red.pdf https://www.uaf.edu/files/olli/OLLI_15_chol_4_red.pdf Checkout slides 7 and 8. My simple understanding is that the sugar creates a particle that provokes an immune response. Cytokines attack the sugar-lipid particle that has been oxidized.
      - subcosmos 9y ago
        Glucose, in high concentration, reacts with proteins at arbitrary locations, effectively gluing them together. This is bad, so the immune system detects this (with a receptor called RAGE) and sends in reinforcements to eat the mess up. https://en.wikipedia.org/wiki/RAGE_(receptor) https://en.wikipedia.org/wiki/RAGE_(receptor)
    - subcosmos 9y ago
      There's compelling evidence that inflammation can cause insulin resistance and fat accumulation, and that insulin resistance and fat accumulation can further cause inflammation. We've found signaling pathways in the body that connect in both directions. So yeah, the causality is actually circular, which in the context of human health implies that a snowball effect is in fact occurring. Escaping this feedback loop is the hard part that we are still working on in the lab.
- thephyber 9y ago
  Not a medical professional, but... Athletes feel aches and pain from inflammation of their muscles. Old persons frequently have inflammation in their joints which causes pain and stiffness. Asthma sufferers have inflammation in their lungs. Anyone (except hemophiliacs) who receives a skin cut has inflammation at the site of the cut. It's an immune response and is a level of abstraction away from the actual observable symptoms, hence the general confusion about what it is.
  - throw132890123 9y ago
    Right I've heard of those examples, but they have nothing to do with diet. So when people say 'eating sugar causes inflammation' what do they mean? How is THAT inflammation felt?
    - dragonwriter 9y ago
      > Right I've heard of those examples, but they have nothing to do with diet. They do, in fact; a pro-inflammatory diet makes the threshold at which symptoms are felt from any of those other source lower, because inflammation has a substantial systemic component. (It may produce unique symptoms of its own, too, but I think the main dietary concern with inflammation is systemic contribution to lowering thresholds to inflammatory symptoms when other triggers are present.)
    - subcosmos 9y ago
      Bad diet causes brain inflammation. You don't feel pain in this case, but you feel tired and hungry, because the part of the brain getting inflamed specifically regulates metabolism and appetite. We know there is inflammation there because the brains immune system goes apeshit, and we can see this under the microscope. Gliosis is the technical name.
    - tqkxzugoaupvwqr 9y ago
      From my own experience, when I eat too much food that contains high amounts of sugar, I start feeling like I’m getting a cold. I get a sore throat, feel much less energetic, like my body is fighting a disease, skin on my head starts itching and turns red, my nose starts shedding. The symptoms get worse when I keep eating high amounts of sugar. When I feel an onset, I avoid sugar to starve the inflammation. High amounts of sugar that trigger the symptoms means >100g in 24 h or >60g per day over several days. The effect also depends on the food, probably because of how it is digested. Sugary water (fruit juice, soda) is worse than solid meals. Some forms of sugar are worse than others, e.g. I can eat some chocolate in moderation but others (e.g. Milka) I get a soar throat within minutes of eating a single piece (<10g).
- ChuckMcM 9y ago
  It is the new "bad" thing and thus gets a lot of press lately but it is also probably true that you have hear many complaints, you just may not have associated them. A sore throat, is caused by inflammation of the mucus tissues in your throat, for example. A mosquito bite itches due to inflammation, it is the immune response to the mosquito's saliva that you feel as an itching sensation. The 'new' thing however is that this mechanism can occur pretty much in every cell of your body and some people have speculated it is the root of a number of ailments. Google 'inflammation' on scholar.google.com and you will find a number of papers discussing different ways that it can affect you.
  - throw132890123 9y ago
    > Google 'inflammation' on scholar.google.com and you will find a number of papers discussing different ways that it can affect you. No thanks, I'm specifically asking for an explanation of how it affects me.
    - ChuckMcM 9y ago
      Mail me a blood sample. :-) More seriously, your question, as stated, can only be answered by your doctor and then probably only after taking various samples. What is worse is that inflammation is typically a response to something else, so it is at least a second order symptom rather than a primary cause. (for example your sore throat is from inflammation, but the inflammation is from a response to something the mucus membrane didn't like. Could be a cold, it could be the chlorine you drank.) Symptoms associated with inflammation are aches, pain, vomiting, diarrhea, fainting, swelling, and itching at least. If you have any of those symptoms, it is affecting you.
    - subcosmos 9y ago
      What YOU (sometimes) feel is pain, redness, and swelling. What your cells feel, are signals from your immune system (cops) to "freeze and stop doing shit". This message is delivered in the form of cytokines. What happens inside the cell, is metabolism slows, and recycling begins. Too much of this leads to atrophy. At the organ level, this causes various diseases of aging. Muscle wasting. Brain atrophy. Liver disease (alcoholic or dietary).

maxxxxx 9y ago

If you are like me then sugar will give you joint pain, headaches and sometimes fever like symptoms. Very noticeable. I wouldn't generalize this though. What has a negative impact on me can be perfectly fine for you.

criddell 9y ago
You know - I've just noticed this myself. If I eat a lot of sugary foods, I often almost feel hungover the next day.
- maxxxxx 9y ago
  I really noticed this only when I stayed at a Yoga Ashram for a month. After two weeks of eating only rice, lentils and vegetables all the little aches I was used to have were gone. I had had no idea how good I could actually feel.

delhanty 9y ago

I don't understand what it means either. But one thing I've picked up is that inflammation isn't all bad - in fact some of it is necessary, particularly for growth. Obviously, as you get older growth becomes less necessary, and cancers very much like to grow too ... so there is a trade off going on and the balance shifts so that inflammation is less desirable as we age. A couple of good inflammation for growth examples: Wound healing has an inflammatory phase. [0] "There is a known relationship between inflammation and muscle growth.For instance, high doses of anti-inflammatory medicines (e.g., NSAIDs) are able to blunt muscle growth." [1] [0] https://en.wikipedia.org/wiki/Wound_healing#Inflammatory_phase https://en.wikipedia.org/wiki/Wound_healing#Inflammatory_pha... [1] https://en.wikipedia.org/wiki/Inflammation#Post-inflammatory_muscle_growth_and_repair https://en.wikipedia.org/wiki/Inflammation#Post-inflammatory...

randomstudent 9y ago

This is a very important question, which I'll try to answer as clearly as possible. First, a word of warning: This doesn't look like the appropriate kind of article to be posted on HN. As a doctor, it's hard to understand all that's going on, and even harder to appreciate what the real impact of this research is. Laymen should completely ignore this kind of articles, and read instead clinical trials or meta-analysis that report practical outcomes people are actually interested in, like life expectancy, cure rates, exercise capacity, weight loss, etc. This paper is about some molecular mumbo-jumbo that is not very interesting in itself, unless you're a researcher in the area. Now, to answer the question. Classically, inflammation was defined by Celsus and Galen as 5 cardinal signs (in latin): - Tumor (swelling) - Calor (warmth) - Rubor (redness - more noticeable in light skin; don't forget that Celsus and Galen worked primarily with patients from Europe and the Middle East) - Dolor (pain) - Functio laesa (loss of function) These are clinical signs, that is, something the doctor can observe at the bedside. Think of when you fall and hurt your knee: the area where the impact happens swells. It might become warm to the touch. The skin might become red (different from bleeding). You'll feel pain, and for a while, your knee won't work very well because it hurts (loss of function). You don't need any fancy equipment to analyse these signs. Now, these are adaptations of the body to injury: redness and warmth appear because the blood vessels in the skin dilate in response to injury. Blood brings red blood cells, which caus redness, and heat from the inside of the body, which causes the skin to be warm to the touch. The blood vessels also "open holes", which causes the liquid part of the blood to escape the bloo vessels and get between the cells, thus causing swelling. The injured cells release signalling substances, which are detected by neurons in the skin, thus causing the individual to feel pain. Finally, some or all of these changes, might cause the limb to lose it's usefullness (because it hurts and it's swollen). The goal of inflammation is to bring white blood cells to the place of the injury in order to fight a possible infection and assist in the repair of the injured tissue. Pain doesn't help protect or repair the tissue directly, but it notifies the organism to the fact that something wrong is happening, which causes the brain to act appropriately: remove the limb from a hot surface in the case of a burn, protect a wound, etc. People that are not sensitive to pain have serious problems from childhood because they lack these indirect protective responses (they won't remove their hand from burning coals, even as they smell their flesh burning, for example) This is the classical picture of inflammation, caused by a wound or trauma to the body. It's simple, and it's functions are (nowadays) obvious. But we can go deeper... Let's talk about pneumonia. Pneumonia happens when a bacteria or virus overwhelms the defenses of the lungs, and starts reproducing in the normally microorganism-free lung. This causes blood vessesls to upen up (thus causing swelling), to dilate (thus causing redness), but the lung probably doesn't get any warmer - it's already pretty warm. The patient will not feel pain. After all, the inside of the lung doesn't have nerves capable of feeling pain! (the outside does, and if the inflammation gets near the peripheral part of the lung, it might be VERY painful). Maybe the lung won't get any warmer (it's already pretty warm already). You will run a fever, but that's not the same kind of warmth we've discussed. You will feel breathlessnes, that is, loss of function of the lung. So, while some things are common the picture gets murky. Also, the body is working very hard to defend itself, and is now producing lots of molecules that circulate in the blood and which we associate with "inflammation". We now need some fancy equipement to detect these molecules: our 5 senses are not good enough. Even though the swelling if the lungs can be detected by auscultation (with a stethoscope), the doctor probably use somethin like an X-Ray machine to visualize the swelling. Let's go deeper. Some bacteria enter the bloodstreem and latch to a valve of the heart. This kind of infection is called an endocarditis. The valve has no blood vessels, so you won't get swelling. You won't get redness or warmth either (again, you ill run a fever, but that's different). The valve also has no nerve endings, so you will feel no pain! The bacteria will happily eat your valve away (and when it's eaten away you'll die), but it may take time, and meanwhile, the valve can work relatively well. So, no loss of function. Yet, your body is fighting in overdrive to clear the infection and kill the bacteria. In fact, lots of mollecules associated with inflammation are running wild all through the body, sometimes causing as much damage as the infection itself! These are the same mollecules your body produces in pneumonia, and also in other kinds of "deep" infections. So, in a sense, even though we have amost none of the 5 classical signs of inflammation, we have a response of the body that aims to defend it against infection. So we might decide to call it inflammation. Again, we can't see the inflammation here. We need some fancy machines to see the damaged valve (even though we can listen to the valve failing with a stethoscope), and fancy lab equipment to detect these molecules, as well as the consequences of the inflammation inside the body. If we go even deeper, we'll "discover" that heart attacks (technically "myocardial infarctions") are the result of inflammation too. Even though what the patient feels is just pain, possibly followed by loss of function: breathlessness and death. So, at each step, we get further removed from the intuitive description of inflammation, which you can feel with your hands and see with your eyes, into a scary realm only accessible with the help of lab equipement and thick books. At this point, inflammation is actually a buzzword that means little... This paper's conclusion doesn't mean that the hypothalamus (a part of the brain) is red, swollen, warm, painful or has stopped functioning. That would be an encephalitis, an extremely serious disease that will land you in a hospital or a coffin (see the movie "Contagion" for some realistic depictions of encephalitis). It means that some cells, vaguely associated with inflammation, are producing some mollecules which in most parts of the body are associated with inflammation. In most situations, inflammation is either bad or signals something bad. In this situation it certainly seems bad: the concrete changes that inflammation brings to the brain seems to be similar to the ones caused by diabetes (according to my cursory reading of the article). But I agree that the word has been used for so many things, that you can't actually tell whether inflammation is good or bad. On the other hand, inflammation is a defense mechanism of the body. So what is a person with no inflammation at all? It's a person really close to death, because Nature is scary and full of bugs, and someone incapable to mount an inflammatory response is what bacteria, viruses and fungi call dinner. People like these exist (either from birth or due to unfortunate circumstances), and we can only keep them alive by keeping them in very clean rooms and pumping them full of antibiotics until their immune system (and the capability to mount an inflammtory response) recovers. Using the same word for what protects us from infection and for what turns our brains into something similar to the brains of a person with untreated diabetes is confusing. We're at a point where when a doctor talks about inflammation, it has a dompletely different thing in mind from laymen. A doctor might even have something completely ifferent in mind from another doctor or from a researcher (which is more serious). In the end, I have nothing to tell you except that you're right to be confused, and if it serves as a consolation, I'm often similarly confused when I read the titles of these papers (and sometimes the abstracts), even though I've been studying these things for years.

cgh 9y ago

In the context of this study, inflammation of the hypothalamus can lead to various diseases, including metabolic syndrome and cardiovascular disease. Metabolic syndrome in particular is interesting because it's a cluster of symptoms that includes high blood sugar and obesity. It's long been known that low-carb/ketogenic diets are an effective treatment for it. You wouldn't actually feel hypothalamic inflammation. You'd eventually just get fat and ill.

pella 9y ago
> It's long been known that low-carb/ketogenic diets are an effective treatment for it. maybe related: cell: "Ketogenic Diet Reduces Midlife Mortality and Improves Memory in Aging Mice" ( 5 September 2017 ) http://www.cell.com/cell-metabolism/fulltext/S1550-4131(17)30489-8 http://www.cell.com/cell-metabolism/fulltext/S1550-4131(17)3... BHB == ketone body beta-hydroxybutyrate "These signaling functions suggest that BHB might itself regulate inflammation and gene expression, with implications for health and longevity. Aberrant inflammasome activity is associated with a variety of age-related diseases (Goldberg and Dixit, 2015), while moderate inhibition of histone deacetylases is associated with enhanced longevity in invertebrates (Woods and Rogina, 2016) as well as amelioration of cognitive decline (Penney and Tsai, 2014) and cardiac dysfunction (Morales et al., 2016) in mice."

pygy_ 9y ago

Inflamation is the response of the immune system to chemical signals sent by the cells of damaged tissue. Depending on the affected organ, the consequences are different. However, the mechanism at the cellular level is mostly identical. Inflamed tissue releases messengers in the blood stream that can be detected (e.g. CRP, orosomucoid, etc...). The process is generally beneficial (helps fight a threat) but it can be triggered by false positives, and the activation of the immune system can dammage healthy tissue. Too much inflammation as a reaction to a real threat can also be problematic, hence the various anti-inflamatory treatments (NSAID/corticosteroids). In this case, prossibly nocive inflammation was discovered in the hypothalamus, the part of the brain that regulates appetite among many other vegetative functions.