All right, I'm gonna start out thanking the committee, organizing committee to invite me for this talk. And disclaimer up front that it is very hard to like talk what Dr. Wischmeyer and both the previous speakers have done already. So that's my, you know, excuse up front. So how do I advance next? All right, other than NIH funding, I have nothing to disclose. In the next few minutes, we'll talk about sepsis mortality in elderly, not that we need to delve deeper into this for this group. We'll talk about immunosenescence and inflammation and how microbiome affects aging and sepsis and vice versa. And maybe we'll draw some very simple conclusions that will be very obvious. We all know that the immune response in sepsis transitions from the hyperinflammatory to a persistent inflammation immunosuppression syndrome. I talked about it this morning. Oh, hang on. It's not advancing. How do I advance this? I think the question is to advance it. Maybe just, just go ahead and click, just click the mouse button on the left. Oh, just click the left button? Yeah. Okay. All right, thank you. So the immune response in sepsis, so what changes this immune response? What facilitates as aging and other comorbidities do this? So we all know, I'm sure we can relate to this, that aging in elderly or sepsis in elderly is deadly. Of the people who die of sepsis, about 65% constitute of people over the age of 65, but the elderly population in the United States is only 12%. So you can see the discordance right there. And it is costly. While we were all very busy with COVID, Dr. Buchman et al came up with this study, fantastic study that was looking at the Medicare beneficiaries data and comparing between 2012 and 2018. And they noticed that they have reported that the sepsis admissions rose from 800,000 to over a million people per year. And the cost of inpatient care rose from 17 to 22 billion. And the SNF cost importantly, I believe, increased from almost 4 billion to $5.6 billion. So what about the comorbidity? What about the aging that affects the sepsis outcomes? And its association with all the other comorbidities such as COPD, dementia is also an independent risk factor for sepsis mortality. Cancer chemotherapy, we can all relate to that. Type 1 and 2 diabetes, cardiovascular disease, et cetera. And the last but not the least, intestinal barrier dysfunction. All these contribute to adverse outcomes in aging with sepsis. So close to about 400 people, give or take, over the age of 65, the incidence is about 400 people per 100,000 population die of sepsis. But if you look at the breakdown that is shown by CDC, between 65 to 74, all the way up to over 85, there is a linear increase, meaning thereby, age is directly proportional to the number of deaths. So what happens with aging? What happens to the immune system? Turns out that the immune system in older adults accumulates all the immunological experiences over time, starting in utero. And they use this immunological memory. And successful aging, as it turns out, what I mean by that is those people in the late 90s and over 100 years of age, they reduce the predisp, or their immune system is able to reduce the predisposition for this excessive or persistent inflammatory response by putting out just right amount of effective anti-inflammatory response. As in, the effective anti-inflammatory response is actually the savior in this case. So that brings me to immunosenescence. The term actually got a very bad rep initially. It had a very negative connotation, but now it sort of has changed over time. And obviously, when something changes over time, in definition, it makes it more vague. That's just the way it is in critical care. So by definition, it's a dynamic process where several immune system functions are reduced, others remain unchanged or increased. Well, that sounds vague, right? So what it comes down to is an adaptive response that balances between chronic inflammation and inflammation we'll talk about in a second, and the anti-inflammatory response. Like I said, the anti-inflammatory response is important for delaying the aging-related diseases. So what is inflammation? So just like hallmarks of cancer, there are hallmarks of aging, many of those. But at the core of them, there is genomic instability with impaired DNA repair processes, which of course, as you can see, it makes you, one, more prone to increased incidence of cancer. There are epigenetic changes, for example. Sirtuin is a best example of that. That's what I study, so that's what comes to mind, is because these are the deacetylators and anti-inflammatory molecules, and are first described, were first described in aging literature. As we age, the sirtuin levels go down, and that makes it, so that makes your histone more prone to acetylation, and pro-inflammatory values persist. We cannot stop talking about this without talking about proteostasis and autophagy, which is an important process in the cellular process by which unfolded, misfolded proteins and the misregulated sort of DNAs and pathogens are destroyed, and that process is impaired with aging. And so that then leads to endoplasmic reticulum as well as mitochondrial stress, and so chronic inflammatory response, and impaired nutrient sensing, as we all know. So how, this lecture is about microbiome. What does microbiome got to do with any of this, right? Turns out that the microbiome actually drives this inflammation. As you can see here, it's a, it's, if you look at the top healthy gut, there is a nice little mucus layer, then there are antimicrobial peptides, the MPs, then there is epithelial layer, and then there is lamina propria. Aging-related gut dysbiosis now is associated with, first of all, thinning of the mucus membrane. The gut mycobacteria are changing, microbial composition changes, and we'll see about that in a minute. Along with that, there is decreased amount of AMPs, these antimicrobial peptides, and then the epithelial cells are unable to repair themselves as fast as they would in a young person. And so that's, and then the tight junctions are also impaired. So putting all this together, there's a perfect storm where the gut pathogens that have changed, I mean, microbes that have changed and more pathogens exist in the gut. Because of the low mucus layer, they come in contact with the epithelial cells and add to that with decreased amount of natural antipeptide function. Now those damaged epithelial cells are unable to repair themselves, and now because of the barrier function dysregulation, you have, there is a gain, these pathogens gain entry into the lamina propria where now you have all kinds of ILCs, telomphasites, macrophages, and neutrophils. They all create a milieu of ongoing inflammatory response, and that now starts to fuel chronic inflammation or inflammation. Turns out that the microbiome also changes in elderly. It ages with the host, and that it changes in diversity. Dr. Vishma has spoke about the alpha diversity or the diversity of microbiome, more the better. And so you have, as we age, we have decreased abundance of core common cells, and there is increased amount of opportunistic microbes, and there is a change in virulence. As is seen by this reference number five, it's a very nice demonstration. They took the fecal samples from old or aged mice versus young mice, made a fecal slurry out of it, and gave it to young mice intraperitoneally to cause sepsis. And when they saw, what they saw was the mice that got fecal peritoneitis from old fecal slurry, if you will, they had more mortality compared to those who got the young mice fecal slurry. So that means, that's an indirect sort of suggestion that the virulence of the older microbiome was also higher. The group down in Florida, they did, sorry, this is Emory group, they did fecalization and puncture, and they set out to look at the effect of microbiome. So they bought mice from two different sources, two different vendors, the same exactly identical genetic background, Jackson versus Charles River, and they made them have the exact identical fecalization and puncture, and look at their mortality, their mortality was different. And Jack's mice had a significantly higher mortality compared to Charles River mice. When they started looking at the diversity of the microbiome, I know it's a busy slide, but the red is higher than the blue, meaning there by the alpha diversity. In the Charles River mice was much higher than the Jackson mice even before they got, or without getting sepsis in Sham group. What they also saw was Sham in Jack's versus Charles River had a different beta diversity between groups. And then the septic mice, of course, the sepsis microbiome was different from respective Sham, but the septic Jack's was different from septic Charles River. As is demonstrated here, there were a higher number of firmicutes, the good guys, even in septic mice from Charles River compared to the Jack's, and bacteroidetes was decreased in these. Along with that, what they showed was in the intestinal epithelial or immune cells, there was more effective, more efficient of T effector and T cells, and CD4 positive cells. What they did then was they co-housed the Jackson's called Charles River mice, and they showed that their microbiome started to be on top of each other. There's no difference. And the survival with sepsis was much better in the co-housing mice or significantly higher survival in co-housing mice compared to the Jack's mice. So what we can draw a conclusion from that is that the microbiome seems to be driving sepsis outcomes. Is the microbiome, oh, that's mouse sepsis. What has that got to do with humans, right? So Lew et al., what they did was they took fecal samples from sepsis patients versus healthy, and what they showed in this article was in sepsis fecal content, they had a decreased alpha diversity in that microbiome versus healthy. They had a higher relative abundance of proteobacteria and actinobacteria, and they had decreased abundance of firmicutes, so good guys. So clearly the microbiome in septic patients is changing. So does sepsis change microbiomes? So the Florida group did this study. They took old versus young mice, gave them sickle ligation and puncture, but looked at their microbiome diversity at baseline and seven days post-sepsis, and what they show was the alpha diversity at the outset, even without making them septic, was very different between old versus young. When the mice, when they became before and after, when they did the before and after comparison, the old or aged mice showed that there was a significant difference in the microbiome diversity in the sepsis, post-sepsis versus pre-sepsis, whereas the young microbiome did not change that much, meaning thereby the young mice were able to keep up their microbial sort of diversity, but not the old mice. So with that, we can draw some simple conclusions that the sepsis in elderly is deadly, we all knew that. Microbiome ages with the host and becomes less diverse and more virulent. Inflammation is driven by dysbiosis, and dysbiosis worsens sepsis outcomes in elderly, and sepsis in elderly changes the microbiome. With that, I would like to thank NIH for my support for whatever I do in life, and thank all of you for paying attention and open this for questions. Thank you.

sepsis

immunosenescence

microbiome

elderly mortality

dysbiosis