Session 2: The Inflammatory Response: Activation of the Innate Immune System
Transcript of Part 2: Inflammation and Disease Tolerance: Surviving Acute Illness
00:00:15;00 Hello. 00:00:16;00 My name is Ruslan Medzhitov. 00:00:17;00 I'm a professor at Yale University School of Medicine and an Investigator of the 00:00:22;00 Howard Hughes Medical Institute. 00:00:23;13 And in this lecture, I will discuss our recent study on the effect of inflammation in acute illness 00:00:30;11 and the role of disease tolerance in surviving acute illness. 00:00:39;11 As I discussed in the introductory lecture, the costs of inflammation can be broken down 00:00:44;01 into two categories. 00:00:45;10 The first is the intentional suppression of lower priority functions that are incompatible 00:00:51;00 with the goals of the response. 00:00:53;17 And the second type of costs are unintentional but unavoidable loss of function, for example, 00:01:00;05 due to collateral damage. 00:01:02;22 And the sum of these two costs has to be lower than the benefit provided by the inflammation 00:01:07;18 in order to... for the system to evolve the way it is. 00:01:12;28 And this relation between the cost and benefit is what's really essential for understanding 00:01:17;14 many biological functions and their deviations into pathological states. 00:01:22;11 So, every biological trait can be characterized by some benefit it provides and some cost 00:01:28;14 at which it operates. 00:01:30;10 And this can be schematically shown as follows. 00:01:32;26 So, if we plot benefit versus cost for a system, for a biological trait to evolve the benefit 00:01:41;06 has to be higher than the cost. 00:01:43;03 So, any trait that would be in the green triangle part of the plot, where the benefit is higher 00:01:48;27 than the cost, would be evolutionary acceptable. 00:01:54;01 And anything in the red triangle, where the cost is higher than the benefit, would be 00:01:57;25 eliminated by natural selection. 00:02:00;28 And as you can see, the higher the benefit of the trait the higher is the acceptable cost. 00:02:07;27 And this view is from the evolutionary perspective. 00:02:11;14 So, all evolution cares about is that the benefit is higher than the cost. 00:02:17;22 And the same plot from the patient or physician perspective would look like this. 00:02:22;21 Here, again, anything that is in the upper-left triangle, where the benefit is higher than 00:02:29;16 the cost, would be a fair game from evolutionary perspective. 00:02:32;27 But as you move to the right side, when the cost becomes higher and higher, because benefit 00:02:38;09 is high, then this would be associated with conditions we would often refer to as 00:02:44;19 pathological or disease conditions. 00:02:46;09 So, if you're a patient and you're having an acute infection, there are ongoing 00:02:52;07 immune and inflammatory responses, but at the same time you feel very ill as a consequence of 00:02:56;21 these responses. 00:02:59;04 This would be a situation in the upper-right corner, where the benefit is still higher 00:03:04;24 than the cost, but the cost is so high that it makes us feel sick. 00:03:10;03 And it is this position on the plot, on the upper-right corner, where trades that provide 00:03:19;00 very high benefit will have very high acceptable costs. 00:03:22;22 And some diseases can be due to these types of trades, with very high benefits coming 00:03:28;28 with the high costs. 00:03:30;08 And that's the situation we've been interested in investigating. 00:03:34;13 What kind of mechanisms operate when the cost of the response is so high that it makes you 00:03:39;10 feel ill, and you're in fact close to the... to the condition where it could be life-threatening? 00:03:48;01 And one famous set of conditions like this is associated with acute illness. 00:03:53;23 And what's been known for... for a long time is that, during acute illness, 00:03:58;19 humans and other animals experience what's known as sickness behaviors. 00:04:04;04 And these are stereotypical responses that include loss of appetite, social withdrawal, 00:04:11;06 fatigue, altered sleep patterns, cessation of grooming, and suppression of libido. 00:04:17;10 And why they all happen and why there's this particular combination of behaviors is 00:04:23;12 not very clear, but it's clear that they occur in all animals studied. 00:04:28;24 They've even been observed in insects. 00:04:31;23 And it's been concluded, decades ago, that these are not just debilitations of 00:04:40;18 normal behaviors, but rather these are motivated behaviors. 00:04:43;21 In other words, they occur with a purpose. 00:04:46;14 There is some intentional induction of these responses. 00:04:50;26 But what the purpose of these responses is... is... has been less clear. 00:04:54;28 And that's what we investigated in this study I will describe today. 00:04:59;14 So, we were particularly interested in understanding the phenomenon of disease-induced anorexia. 00:05:09;23 We are all familiar with this phenomenon. 00:05:11;19 When you have acute infection, like flu infection or a severe cold, your appetite goes away. 00:05:18;01 You don't want to eat. 00:05:19;02 You want to sleep a lot. 00:05:20;17 And we asked why is it that we don't eat when we are very sick. 00:05:25;18 And to model that, we studied an infection with a bacterial pathogen called 00:05:32;18 Listeria monocytogenes, which is a very common bacterium that causes food poisoning. 00:05:39;11 And what we did... here, we infected mice with a sublethal dose of Listeria and monitored 00:05:47;18 their food consumption. 00:05:49;09 And as you can see, the red line is mice that are infected with Listeria, and as you 00:05:55;18 can see there is a very profound suppression of food consumption. 00:05:59;28 And go on... into this anorexic state until they start recovering from infection, 00:06:06;26 at which point they will regain food consumption. 00:06:11;08 And we asked, why is it that they don't eat? 00:06:13;21 What would happen if they are forced to eat? 00:06:17;27 And to address that, we fed the mice with the same amount of the same type of food 00:06:24;15 that they normally consume. 00:06:26;16 And we only provided them about 20 percent of normal daily caloric intake. 00:06:32;26 So, it's just a small fraction of what they would normally eat. 00:06:36;28 And we used, in this case, a dose of Listeria that kills 50 percent of mice -- so it's called 00:06:43;02 lethal dose 50 or LD50 -- which is shown in the black line. 00:06:47;25 These are mice that are control mice. 00:06:51;15 And then the experimental mice were given food. 00:06:54;03 And as you can see, all of them died within 10 days, indicating that eating during bacterial infection 00:07:01;17 can be lethal. 00:07:03;13 And that result actually is not new. 00:07:05;02 It was first reported in 1979 with a similar model, with Listeria infection, that force-feeding 00:07:11;08 during infection can be... it can lead... can increased... it can increase lethality. 00:07:16;28 So, then we asked, what is it in the food that causes this effect? 00:07:21;14 And we tested, separately, proteins, carbohydrates, and fats. 00:07:26;19 And found that the effect of the... this effect of feeding was due to carbohydrates, 00:07:32;22 specifically due to glucose, because if we would just give mice glucose at the time of the... of the infection, 00:07:39;25 then 100% of them would succumb to infection. 00:07:45;07 And that was very interesting because it indicated that just glucose -- that simple metabolite, 00:07:50;07 an essential metabolite -- is sufficient to cause such a dramatic effect on survival. 00:07:56;24 And then we asked, what would happen if we do the opposite manipulation, if we 00:08:02;20 prevent glucose utilization? 00:08:04;21 And to do so, we used a metabolite derivative called 2-deoxyglucose, or 2DG, which is 00:08:12;02 a glucose variant that can be taken into the cells but cannot be metabolized, so it 00:08:16;18 prevents glucose utilization even if glucose is present in the system. 00:08:22;00 And when we gave mice 2DG twice a day, by injecting it either intraperitoneally or 00:08:29;01 giving it orally or giving it intravenously... it didn't matter which route we used. 00:08:35;16 And as you can see in the blue line here, 100% of mice now could survive this infection 00:08:41;12 that otherwise would kill 50% of mice. 00:08:44;04 So, that was very exciting because it indicated that blocking glucose utilization can 00:08:50;03 protect mice from infection, and giving them glucose can promote mortality. 00:08:57;22 Then we asked whether this is something unique to Listeria or can be generalized to 00:09:02;20 other types of bacterial infections. 00:09:05;28 And to address this, we used a common model of bacterial sepsis that is caused by... 00:09:12;21 not by live bacteria but by specific a bacterial component called lipopolysaccharide, or LPS, 00:09:19;17 which is present in all gram-negative bacteria and which is well-known to induce a very dramatic 00:09:25;20 inflammatory response. 00:09:27;07 So, inflammation caused by gram-negative infections is in large part due to LPS. 00:09:32;24 So, if we just use LPS instead of live pathogens, then we simplify the system and 00:09:38;04 eliminate all the variations due to pathogenicity of different bacteria. 00:09:44;21 And as you can see here, we... when we give an LD50 dose of LPS, which is the line 00:09:50;22 in the middle, we have about 50% of mice that would succumb to sepsis. 00:09:56;11 Then, if we give them either a control -- PBS, phosphate... phosphate-buffered saline, 00:10:03;22 a physiological solution -- or give them food, you can see that there's a dramatic difference 00:10:08;01 in survival. 00:10:09;01 So, mice that received food, most of them would die. 00:10:13;09 And then we asked if this effect, again, is due to glucose. 00:10:16;19 And we performed, again, a similar experiment, giving either glucose or 2DG. 00:10:23;24 And as you can see, now 100% of mice that received glucose would die from LPS sepsis, 00:10:31;00 and 100% would survive if they are given 2-deoxyglucose. 00:10:34;17 So, this was very exciting because this is a very simple manipulation. 00:10:38;22 We're just using either glucose or anti-glucose. 00:10:43;01 And we have this profound, 100% effect on survival in a condition that is 00:10:51;05 otherwise intractable. 00:10:52;16 It's uhh... sepsis is a very complex disease that has a very high mortality rate, 00:11:00;11 and there are still very few treatment options for sepsis. 00:11:02;28 So, we were very excited to see that such a simple manipulation can have such a dramatic 00:11:07;18 effect on survival. 00:11:09;28 Interestingly, these effects of glucose and 2-deoxyglucose were not due to changes in 00:11:17;04 the magnitude of the inflammatory response. 00:11:20;14 So, if we measure the major inflammatory cytokines, including TNF, IL-6, or acute-phase proteins 00:11:28;13 such as serum amyloid protein, you can see that, regardless of whether it's 00:11:33;19 a control mouse or a mouse given glucose or 2DG, the level of inflammatory response was the same. 00:11:39;14 So the fact that mice given glucose died and mice given 2DG survived is not due to changes 00:11:46;02 in the inflammatory response. 00:11:48;04 So, then we asked, what is it due to? 00:11:50;28 And of course, when mice don't eat they undergo a fasting metabolic state. 00:11:57;21 And we then asked whether this fasting metabolism is the one that matters, rather than the inflammation 00:12:03;12 itself. 00:12:05;06 And just to remind you, what happens during fasting is that glucose level goes down and 00:12:12;07 therefore insulin level goes down. 00:12:14;19 And most organs switch from using glucose to switching... to using fatty acids produced... 00:12:23;15 released from adipose tissue. 00:12:25;13 And only brain continues to use glucose, initially. 00:12:28;12 So, during initial stages of fasting, free fatty acids, or FFA, would be released from 00:12:34;27 adipose tissue by a process called lipolysis, or release of fatty acids. 00:12:40;06 And then fatty acids will become main fuel for most organs. 00:12:44;02 And... while brain will continue to use glucose. 00:12:47;24 And then, if fasting is prolonged, then some fatty acids will go into liver and will 00:12:53;15 be converted into a different metabolite called... called ketones, such as beta-hydroxybutyrate, 00:12:59;04 or BHOB here. 00:13:02;06 And this fasting metabolic switch into ketogenesis -- production of ketones -- is controlled 00:13:08;18 by a nuclear receptor called PPAR-alpha, shown here. 00:13:13;06 So, what PPAR-alpha does during this prolonged fasting... it detects fatty acids that are 00:13:19;14 delivered from the adipose tissue and induces enzymes that generate ketones from fatty acids. 00:13:28;06 And the point of that is that ketones now can be used by the brain. 00:13:33;00 And the second thing that PPAR-alpha does, it controls expression of a fasting hormone 00:13:38;02 called FGF21. 00:13:39;15 So, we thought that it's... these PPAR-alpha-regulated processes that are activated during fasting 00:13:47;06 might be involved in controlling survival because when we eat, or consume food or glucose, 00:13:54;12 that would induce insulin production, and insulin will suppress all these processes. 00:13:58;20 It will suppress lipolysis and it will suppress ketogenesis. 00:14:03;00 And we thought that maybe that's why glucose kills and 2-deoxyglucose leads to... 00:14:09;09 promotes survival. 00:14:10;26 So, to test that, we first examined whether, indeed, glucose will prevent these PPAR-alpha-regulated 00:14:20;19 outcomes, such as hydroxybutyrate production and FGF21 expression. 00:14:26;06 And indeed, as you can see on the left side, this is measurement of non-esterified fatty acids, 00:14:32;28 or free fatty acids. 00:14:34;04 So, they are released during fasting. 00:14:35;19 You can see in the black line the fatty acid level in the... in the plasma go up. 00:14:42;25 And later, beta-hydroxybutyrate starts going up and the fasting hormone FGF21 is also 00:14:49;27 strongly induced. 00:14:52;04 But if we give mice glucose, then all these responses are shut down, and none of them happen. 00:14:58;21 And then we asked whether they... this is what contributes to differential survival 00:15:03;13 from feeding. 00:15:05;01 So to address that, we used mice that are deficient PPAR-alpha, where neither ketogenesis 00:15:11;23 nor FGF21 expression can be induced. 00:15:14;19 And we used, also, FGF21 knockout mice. 00:15:18;09 And as you can see in the left panel, both of these mice now succumb to sub-lethal doses 00:15:25;12 of LPS that are survived 100% by control mice. 00:15:30;13 So, that suggested both FGF21 and PPAR-alpha are necessary for survival. 00:15:36;00 And in the absence of PPAR-alpha, on the right panel you can see that there is no production 00:15:40;26 of beta-hydroxybutyrate. 00:15:45;13 But the level of inflammation in all three conditions was the same. 00:15:48;19 So, as you can see in the lower panel, the level of TNF in... in the serum in all three 00:15:55;23 mouse strains was the same. 00:15:59;26 So, what we found also is that glucose supplementation increased, and 2-deoxyglucose decreased oxidative 00:16:09;14 stress in the midbrain area during LPS sepsis. 00:16:13;28 And by performing PET scans to follow where glucose goes during sepsis, we found that, 00:16:20;12 following LPS challenge, the... this area of midbrain was the... showed the 00:16:27;22 greatest difference in glucose consumption. 00:16:29;12 So, there was increased glucose uptake into the... this particular brain area that... 00:16:34;16 where we also saw increased oxidative stress. 00:16:39;08 And so what we concluded from that is that fasting metabolism and ketogenic programs 00:16:45;14 are required for survival of LPS sepsis. 00:16:50;12 And what we noticed also is that the death from sepsis was preceded by seizures or convulsions. 00:16:57;01 And it's also well-known that ketogenic diet is used to treat epilepsy. 00:17:02;01 And all these pieces of the puzzle together led us to ask whether anti-epileptic drugs 00:17:08;04 could be protective from sepsis, which was a very far-fetched idea. 00:17:12;17 But we tested it and, to our surprise and delight, we found that, indeed, the anti-epileptic drug 00:17:20;01 valproic acid could rescue mice from lethal sepsis. 00:17:25;24 And interestingly, the second anti-epileptic drug, called Keppra, did not have such an effect. 00:17:31;06 And that is very informative for us because these two drugs have very different 00:17:34;08 mechanisms of action. 00:17:37;02 So, we then tested whether valproic acid can protect upstream or downstream of the effect 00:17:45;22 of glucose. 00:17:47;10 And what we found was that valproic acid protected against LPS sepsis even in PPAR-alpha knockout mice, 00:17:57;12 which as you remember cannot produce ketone bodies. 00:18:02;12 So... as if valproic acid substitutes to the protective effect of ketones. 00:18:08;01 But 2-deoxyglucose cannot protect PPAR-alpha knockout mice from LPS sepsis because it acts 00:18:13;04 upstream of PPAR-alpha. 00:18:15;17 So, that indicated that valproic acid has its effect very downstream in the fasting pathway, 00:18:22;22 at the same level, perhaps, as ketone bodies. 00:18:26;19 And the conclusion to this part is that during sepsis -- endotoxin sepsis, LPS sepsis -- 00:18:37;05 LPS induces inflammatory cytokines, and which of these is most important here is... 00:18:41;16 is not clear, and probably several of them can lead to similar effects of increasing 00:18:47;20 generation of reactive oxygen species in the midbrain area. 00:18:51;25 And glucose promotes this effect and 2DG inhibits it. 00:18:57;08 And ketones also inhibit that effect. 00:18:59;20 And consumption of food or glucose prevents ketogenesis and therefore interferes with 00:19:07;02 the protective effect from... protection from this damage by ROS. 00:19:12;22 And during fasting, a PPAR-alpha-dependent mechanism generates ketones, which lead to 00:19:19;00 reduced ROS production and adaptation to the stress of inflammation, and survival, ultimately. 00:19:26;10 And we think one of the effects, common targets, here, could be histone deacetylase... deacetylases, 00:19:33;11 because both ketones and valproic acid are known to inhibit histone deacetylases. 00:19:38;27 And this is something we are currently testing. 00:19:41;05 So, that's the part of the study that had to do with bacterial infection and bacterial sepsis, 00:19:49;01 where we found that eating during bacterial infection or sepsis interferes with 00:19:55;02 this normal protective effect of fasting metabolism, and therefore the anorexia that we feel 00:20:01;08 when we have infections has to do with promoting these types of protective mechanisms 00:20:09;22 associated with fasting metabolism. 00:20:13;12 And then we... what we found here, therefore, is that this increased glucose level, if it 00:20:21;06 goes above some upper threshold level, can be deadly in the context of bacterial sepsis. 00:20:30;05 And another recent study examined the role of glucose in a very different model, 00:20:35;16 where they looked at the lower threshold level, where they used mice which are unable to 00:20:41;20 produce glucose from the liver. 00:20:44;19 And this was... this... and that also leads to mortality. 00:20:47;20 This was a study by Miguel Soares from Instituto Gulbenkian in Lisbon, where they found that 00:20:53;23 there is also a lower boundary for the glucose level. 00:20:58;10 So, both upper boundary and lower boundary, if they're exceeded in the glucose level, 00:21:03;06 can lead to mortality. 00:21:04;19 So, it's important to keep that in mind, that it's not an excess or depletion; it's a maintenance 00:21:12;00 of the... the right amount of glucose that is required for survival. 00:21:17;00 And this is not surprising, of course, because glucose is still essential for many cells, 00:21:21;25 especially neuronal cells, for survival. 00:21:29;01 And... well, we found this very dramatic effect of glucose and 2-deoxyglucose on 00:21:35;27 bacterial infection in sepsis. 00:21:37;06 We then asked whether this is more a general phenomenon and whether it applies to all infections. 00:21:44;16 And to address that, we used a mouse model of influenza infection, where mice are infected 00:21:52;02 with the flu virus. 00:21:54;04 And in this case, we are giving a sub-lethal dose of flu. 00:21:57;10 And then we follow, again, the food consumption. 00:21:59;26 And just like with bacterial infection, you can see that mice, when they... 00:22:03;19 at the peak of infection, they stop eating. 00:22:06;16 And then as they start recovering from infection, they... they resume food consumption. 00:22:13;02 And we asked again, what would happen if we feed them at the time when they are anorexic? 00:22:20;07 And what we found was very surprising, and opposite to what we expected and opposite 00:22:24;19 to what we found with bacterial infection. 00:22:27;14 As you can see here, if we feed the mice, they actually survive better compared to mice 00:22:32;21 that received control PBS solution. 00:22:36;26 And if we just give them glucose, they also do better. 00:22:40;01 And glucose partially protects from mortality. 00:22:42;14 And we think the... the rest of the protection is provided by sodium. 00:22:50;06 And when we ask the question, the converse question, what 2DG will do, we found that 00:22:56;05 2DG actually was lethal in the context of viral infection. 00:23:00;16 As shown here in the blue line, when mice are given 2DG in the context of viral infection, 00:23:07;04 they all died 100%. 00:23:09;22 Interestingly, this difference in survival was not due to tissue damage that was normally 00:23:16;27 caused by flu virus. 00:23:18;11 So, this is a lung pathology. 00:23:21;06 On the left side is the control and on the right side is 2DG-treated mice, and they're 00:23:26;02 basically the same. 00:23:27;10 There is no difference in the degree of tissue damage caused by the virus. 00:23:31;12 And also there is the same level of hemorrhage, edema, and inflammatory infiltrates. 00:23:37;08 So, that did not explain 100% differences in survival. 00:23:43;06 And also, there was no difference in the magnitude of the inflammatory response, as shown on 00:23:49;27 the left side by measuring interferon-alpha in the plasma. 00:23:55;02 And interestingly and importantly, there's no difference, also, in viral burden. 00:23:59;05 If we measure the amount of viruses during infection, they are similar between 00:24:04;18 control and 2DG-treated mice. 00:24:06;07 And again, 2DG-treated mice are the ones that succumb 100% to this infection. 00:24:12;22 So, what we then noticed, by performing other measurements on these mice, is that 00:24:22;07 the death from viral inflammation caused by either flu virus or some mimics of viral infection 00:24:29;22 was associated with decline in vital functions, such as heart rate, respiratory rate, 00:24:35;00 and so on. 00:24:36;00 And that suggested that there perhaps is a failure of the autonomic control centers that 00:24:40;16 reside in the brainstem. 00:24:43;08 And moreover, when we performed PET scans on these mice, again we found that 00:24:48;09 glucose was preferentially taken into the brainstem area during viral inflammation. 00:24:54;14 And remember, during bacterial inflammation it was preferentially taken into the midbrain area. 00:24:59;24 So, that was puzzling but suggested a possible scenario where viral infection somehow interfaces 00:25:08;09 with glucose metabolism, and the only type of connection that we could find in the prior literature 00:25:15;02 that would suggest the mechanism had to do with endoplasmic reticulum stress, 00:25:21;02 or ER stress. 00:25:22;02 So, ER stress is normally induced by unfolded protein response in the endoplasmic reticulum, 00:25:29;16 and it leads to adaptation to the unfolded protein accumulation through induction of 00:25:35;24 chaperones and various proteases and so on. 00:25:38;06 And that leads to resolution of the ER stress. 00:25:40;13 However, if ER stress is excessive, then the second branch of the pathway is induced by 00:25:49;04 leading to transcriptional induction of a transcription factor called CHOP that 00:25:56;15 leads to cell death through apoptosis. 00:26:00;15 And because glucose availability can also impact on protein glycosylation in the ER, 00:26:05;10 it can also lead to ER stress. 00:26:07;14 So, when cells are deprived of glucose, that can lead to ER stress. 00:26:14;21 And viral infection can also lead to ER stress. 00:26:17;15 So we thought, perhaps these two conditions may somehow conspire to trigger excessive 00:26:24;13 ER stress, leading to induction of this transcription factor, CHOP, leading to neuronal damage in 00:26:30;24 the brainstem. 00:26:33;11 And we tested whether CHOP is indeed induced under those conditions anywhere in the brain 00:26:38;08 and found that, indeed, when mice have viral inflammation -- in this case induced by 00:26:44;24 a viral mimic called poly(I:C) -- either alone or together with 2DG, and then we monitored 00:26:52;02 CHOP expression by Western blot, and we found that it was only induced in hindbrain area, 00:26:59;04 and only when mice received both poly(I:C) and 2DG. 00:27:04;17 And then we tested whether CHOP is involved in mortality caused by infection and 2DG. 00:27:12;18 And to test that, we used either wild-type or CHOP-deficient mice. 00:27:17;12 The gene name for CHOP is Ddit3, so those are Ddit3 knockout mice in open... open symbols. 00:27:25;08 And as you can see, wild type mice that received poly(I:C) and 2DG die 100%; that's the blue triangles. 00:27:32;23 And CHOP-deficient mice receiving the same combination of poly(I:C) and 2DG survive 100%, 00:27:40;10 indicating that, indeed, this particular transcription factor is a critical mediator of mortality 00:27:46;03 from viral infection combined with 2DG. 00:27:50;24 And again, as shown on the right slide, there was no difference in the inflammatory response, 00:27:55;07 as measured here by interferon-alpha in the serum. 00:27:59;12 So, the summary for this part is, during viral infection, or more generally during 00:28:05;03 viral inflammation, because we could find the same exact phenomenon with just using poly(I:C), 00:28:10;26 there is a production of type-1 interferons -- interferon alpha and beta -- and that leads 00:28:15;28 to activation of the unfolded protein response, or UPR, combined with glucose consumption 00:28:29;00 in the brainstem area. 00:28:31;27 Why it's specifically brainstem that's affected in this manner we don't know. 00:28:35;22 It's a very interesting question which we hope to understand someday. 00:28:41;13 But what happens in the context of this response with metabolites is that glucose ameliorates 00:28:48;07 this response -- it prevents induction of CHOP and neuronal dysfunction and... and death -- 00:28:55;19 whereas 2DG exacerbates it and leads to CHOP induction and subsequent loss of function 00:29:03;20 of the brainstem and autonomic control centers, resulting in death. 00:29:09;06 So, these are two very different effects of metabolism on bacterial and viral inflammation. 00:29:16;26 And all of it could be tied down to utilization of glucose or block of glucose utilization. 00:29:25;09 And it's completely independent of pathogenicity. 00:29:29;04 It's independent of pathogen burden. 00:29:32;00 And it's independent on the magnitude of inflammation. 00:29:34;25 So, this is what we refer to as being able to tolerate a given level of inflammation, 00:29:41;09 rather than controlling the level of inflammation. 00:29:44;19 So, this study was done by three very talented scientists in my group -- shown from right to left, 00:29:52;17 Andrew Wang, Sarah Huen, and Harding Luan 00:29:57;09 -- and two talented technicians -- Cuiling and Shuang -- who helped with the study, 00:30:03;15 and... as well as Carmen Booth and Jean-Dominique Gallezot, who are... 00:30:08;27 helped with pathology and PET scans. 00:30:11;20 And our funding is shown at the bottom of this slide. 00:30:15;27 And thank you for your attention.