Necroptosis contributes to chronic inflammation and fibrosis in aging liver

Inflammaging, characterized by an increase in low-grade chronic inflammation with age, is a hallmark of aging and is strongly associated with various age-related diseases, including chronic liver disease (CLD) and hepatocellular carcinoma (HCC). Because necroptosis is a cell death pathway that induces inflammation through the release of DAMPs, we tested the hypothesis that age-associated increase in necroptosis contributes to chronic inflammation in aging liver. Phosphorylation of MLKL and MLKL-oligomers, markers of necroptosis, as well as phosphorylation of RIPK3 and RIPK1 were significantly upregulated in the livers of old mice relative to young mice and this increase occurred in the later half of life (i.e., after 18 months of age). Markers of M1 macrophages, expression of proinflammatory cytokines (TNFα, IL6 and IL-1β), and markers of fibrosis were significantly upregulated in the liver with age and the change in necroptosis paralleled the changes in inflammation and fibrosis. Hepatocytes and liver macrophages isolated from old mice showed elevated levels of necroptosis markers as well as increased expression of proinflammatory cytokines relative to young mice. Short term treatment with the necroptosis inhibitor, necrostatin-1s (Nec-1s), reduced necroptosis, markers of M1 macrophages, expression of proinflammatory cytokines, and markers of fibrosis in the livers of old mice. Thus, our data show for the first time that liver aging is associated with increased necroptosis and necroptosis contributes to chronic inflammation in the liver, which in turn appears to contribute to liver fibrosis and possibly CLD.

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Necroptosis increases with age in the brain and contributes to age-related neuroinflammation

10.1101/2021.07.23.453580 ◽

2021 ◽

Author(s):

Nidheesh Thadathil ◽

Evan Nicklas ◽

Sabira Jazir ◽

Tommy L Lewis ◽

Arlan Richardson ◽

...

Keyword(s):

Term Treatment ◽

Short Term Treatment ◽

Cell Death Pathway ◽

Age Related ◽

A Cell ◽

The Central Nervous System ◽

Layer V ◽

Molecular Patterns ◽

Old Mice ◽

The Brain

Chronic inflammation of the central nervous system (CNS), termed neuroinflammation, is a hallmark of aging and a proposed mediator of cognitive decline associated with aging. Neuroinflammation is characterized by the persistent activation of microglia, the innate immune cells of the CNS, with damage-associated molecular patterns (DAMPs) being one of the well-known activators of microglia. Because necroptosis is a cell death pathway that induce inflammation through the release of DAMPs, we hypothesized that an age-associated increase in necroptosis contributes to increased neuroinflammation with age. The marker of necroptosis, phosphorylated form of MLKL (P-MLKL), and kinases in the necroptosis pathway (RIPK1, RIPK3, and MLKL) showed a region-specific increase in the brain with age, specifically in the cortex layer V and the CA3 region of the hippocampus of mice. Similarly, MLKL-oligomers, which causes membrane binding and permeabilization were significantly increased in the cortex and hippocampus of old mice relative to young mice. Nearly 70 to 80% of P-MLKL immunoreactivity was localized to neurons and less than 10% was localized to microglia, whereas no P-MLKL was detected in astrocytes. P-MLKL expression in neurons was detected in the soma, not in the processes. Blocking necroptosis using Mlkl-/- mice reduced markers (Iba-1 and GFAP) of neuroinflammation in the brains of old mice and short-term treatment with the necroptosis inhibitor, necrostatin-1s, reduced expression of proinflammatory cytokines, IL-6 and IL-1β, in the hippocampus of old mice. Thus, our data demonstrate for the first time that brain necroptosis increases with age and contributes to age-related neuroinflammation in mice.

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Necroptosis increases with age in the brain and contributes to age-related neuroinflammation

GeroScience ◽

10.1007/s11357-021-00448-5 ◽

2021 ◽

Author(s):

Nidheesh Thadathil ◽

Evan H. Nicklas ◽

Sabira Mohammed ◽

Tommy L. Lewis ◽

Arlan Richardson ◽

...

Keyword(s):

Term Treatment ◽

Short Term Treatment ◽

Cell Death Pathway ◽

Age Related ◽

A Cell ◽

The Central Nervous System ◽

Layer V ◽

Molecular Patterns ◽

Old Mice ◽

The Brain

AbstractChronic inflammation of the central nervous system (CNS), termed neuroinflammation, is a hallmark of aging and a proposed mediator of cognitive decline associated with aging. Neuroinflammation is characterized by the persistent activation of microglia, the innate immune cells of the CNS, with damage-associated molecular patterns (DAMPs) being one of the well-known activators of microglia. Because necroptosis is a cell death pathway that induces inflammation through the release of DAMPs, we hypothesized that an age-associated increase in necroptosis contributes to increased neuroinflammation with age. The marker of necroptosis, phosphorylated form of MLKL (P-MLKL), and kinases in the necroptosis pathway (RIPK1, RIPK3, and MLKL) showed a region-specific increase in the brain with age, specifically in the cortex layer V and the CA3 region of the hippocampus of mice. Similarly, MLKL-oligomers, which cause membrane binding and permeabilization, were significantly increased in the cortex and hippocampus of old mice relative to young mice. Nearly 70 to 80% of P-MLKL immunoreactivity was localized to neurons and less than 10% was localized to microglia, whereas no P-MLKL was detected in astrocytes. P-MLKL expression in neurons was detected in the soma, not in the processes. Blocking necroptosis using Mlkl−/− mice reduced markers of neuroinflammation (Iba-1 and GFAP) in the brains of old mice, and short-term treatment with the necroptosis inhibitor, necrostatin-1s, reduced expression of proinflammatory cytokines, IL-6 and IL-1β, in the hippocampus of old mice. Thus, our data demonstrate for the first time that brain necroptosis increases with age and contributes to age-related neuroinflammation in mice.

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Physical performance is enhanced in old mice fed a short term diet medicated with rapamycin, acarbose, and phenylbutyrate

Aging Pathobiology and Therapeutics ◽

10.31491/apt.2021.03.051 ◽

2021 ◽

Vol 3 (1) ◽

pp. 12-13

Author(s):

Megan Ellis ◽

◽

Warren Ladiges ◽

Zhou Jiang

Keyword(s):

Grip Strength ◽

Physical Performance ◽

Healthy Aging ◽

Term Treatment ◽

Drug Cocktail ◽

Short Term ◽

Short Term Treatment ◽

Full Dose ◽

Age Related ◽

Old Mice

Loss of physical performance, as seen in humans by decreased grip strength and overall physical fitness, is generally accepted to be a consequence of aging. Treatments to delay or reduce these changes or increase resilience to them are generally not available. In this preliminary study, 20-month-old male and female C57BL/6 mice were given either a standard mouse diet or a formulated mouse diet containing rapamycin (14 ppm), acarbose (1000 ppm), and phenylbutyrate (1000 ppm), or a diet containing one half dose of each drug, for 3 months. At the end of the study, performance on a rotarod and grip strength test was compared. In general, mice fed the full dose drug cocktail diet performed better on these assays, with significant improvements in rotarod performance in females fed the full dose cocktail and in grip strength in males fed the full dose cocktail, and females fed the low dose cocktail. These observations provide support for the concept that short term treatment with a cocktail of drugs that targets multiple aging pathways can increase resilience to aging, and suggests that this prototype cocktail could be part of a clinical therapeutic strategy for delaying age-related loss of physical performance in people. Keywords: Healthy aging, physical performance, aging processes, anti-aging drug cocktail, rapamycin, acarbose, phenylbutyrate, aging mice

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Excess ω-6 fatty acids influx in aging drives metabolic dysregulation, electrocardiographic alterations, and low-grade chronic inflammation

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00297.2017 ◽

2018 ◽

Vol 314 (2) ◽

pp. H160-H169 ◽

Cited By ~ 15

Author(s):

Vasundhara Kain ◽

Kevin A. Ingle ◽

Maureen Kachman ◽

Heidi Baum ◽

Gobinath Shanmugam ◽

...

Keyword(s):

Fatty Acids ◽

Fatty Acid ◽

Chronic Inflammation ◽

Heart Function ◽

Energy Utilization ◽

Prostaglandin E ◽

Low Grade ◽

Related Factor ◽

Carbohydrate Utilization ◽

Age Related

Maintaining a balance of ω-6 and ω-3 fatty acids is essential for cardiac health. Current ω-6 and ω-3 fatty acids in the American diet have shifted from the ideal ratio of 2:1 to almost 20:1; while there is a body of evidence that suggests the negative impact of such a shift in younger organisms, the underlying age-related metabolic signaling in response to the excess influx of ω-6 fatty acids is incompletely understood. In the present study, young (6 mo old) and aging (≥18 mo old) mice were fed for 2 mo with a ω-6-enriched diet. Excess intake of ω-6 enrichment decreased the total lean mass and increased nighttime carbohydrate utilization, with higher levels of cardiac cytokines indicating low-grade chronic inflammation. Dobutamine-induced stress tests displayed an increase in PR interval, a sign of an atrioventricular defect in ω-6-fed aging mice. Excess ω-6 fatty acid intake in aging mice showed decreased 12-lipoxygenase with a concomitant increase in 15-lipoxygenase levels, resulting in the generation of 15( S)-hydroxyeicosatetraenoic acid, whereas cyclooxygenase-1 and -2 generated prostaglandin E2, leukotriene B4, and thromboxane B2. Furthermore, excessive ω-6 fatty acids led to dysregulated nuclear erythroid 2-related factor 2/antioxidant-responsive element in aging mice. Moreover, ω-6 fatty acid-mediated changes were profound in aging mice with respect to the eicosanoid profile while minimal changes were observed in the size and shape of cardiomyocytes. These findings provide compelling evidence that surplus consumption of ω-6 fatty acids, coupled with insufficient intake of ω-3 fatty acids, is linked to abnormal changes in ECG. These manifestations contribute to functional deficiencies and expansion of the inflammatory mediator milieu during later stages of aging. NEW & NOTEWORTHY Aging has a profound impact on the metabolism of fatty acids to maintain heart function. The excess influx of ω-6 fatty acids in aging perturbed electrocardiography with marked signs of inflammation and a dysregulated oxidative-redox balance. Thus, the quality and quantity of fatty acids determine the cardiac pathology and energy utilization in aging.

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A238 ABSENCE OF AGE-RELATED MEMORY DECLINE IN GERM-FREE MICE

Journal of the Canadian Association of Gastroenterology ◽

10.1093/jcag/gwab002.236 ◽

2021 ◽

Vol 4 (Supplement_1) ◽

pp. 288-289

Author(s):

N Kraimi ◽

G De Palma ◽

J Lu ◽

D Bowdish ◽

E Verdu ◽

...

Keyword(s):

Locomotor Activity ◽

Spatial Memory ◽

Cognitive Decline ◽

Memory Performance ◽

Alternation Rate ◽

Memory Decline ◽

Germ Free ◽

Age Related ◽

Old Mice ◽

Young Mice

Abstract Background Age-associated deterioration of cognitive function and memory capacity occur in a variety of mammals, from humans to rodents. For example, significant memory deficits have been reported in conventionally raised (SPF) old mice compared to conventionally raised young mice submitted to a spatial memory task (Prevot et al., Mol Neuropsychiatry 2019). Microbiota to brain signaling is now well established in mice, but the extent to which this influences age-related memory decline is unknown. Aims Our project aims to determine whether the intestinal microbiota contributes to age-related changes in brain function. We address the hypothesis that age-related cognitive decline is attenuated in the absence of the intestinal microbiota. Methods We studied locomotor behavior and spatial memory performance in young germ-free (GF) mice (2–3 months of age, n=24) and senescent GF mice (13–27 months old, n=22) maintained in axenic conditions, and compared them to conventionally raised (SPF) mice. We used the Y-maze test based on a spontaneous alternations task to assess cognition, with alternation rate as a proxy of spatial working memory performance. The locomotor activity was measured using the open-field test. Results GF old mice traveled less distance (458.9 cm) than GF young mice (875.7 cm, p < 0.001) but these differences in locomotor activity did not influence spatial memory performance. Indeed, both GF old and GF young mice had an identical alternation rate of 73.3% (p > 0.05). This contrasted with the memory impairment found in old SPF mice that displayed lower alternation rate of 58.3%, compared to that found in young SPF mice (76.2%, p = 0.13). Conclusions We conclude that the absence of age-related memory decline in germ-free mice is consistent with a role for the microbiota in the cognitive decline associated with aging, likely through action on the immune system, well documented in SPF mice (Thevaranjan et al., Cell Host & Microbe 2017). We propose that novel microbiota-targeted therapeutic strategies may delay or prevent the cognitive decline of aging. Funding Agencies CIHRBalsam Family Foundation

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The Roles of the Gut Microbiota and Chronic Low-Grade Inflammation in Older Adults With Frailty

Frontiers in Cellular and Infection Microbiology ◽

10.3389/fcimb.2021.675414 ◽

2021 ◽

Vol 11 ◽

Author(s):

YuShuang Xu ◽

XiangJie Liu ◽

XiaoXia Liu ◽

Di Chen ◽

MengMeng Wang ◽

...

Keyword(s):

Older Adults ◽

Gut Microbiota ◽

Chronic Inflammation ◽

Healthy Aging ◽

Low Grade ◽

Age Related ◽

Composition Structure ◽

Low Grade Inflammation

Frailty is a major public issue that affects the physical health and quality of life of older adults, especially as the population ages. Chronic low-grade inflammation has been speculated to accelerate the aging process as well as the development of age-related diseases such as frailty. Intestinal homeostasis plays a crucial role in healthy aging. The interaction between the microbiome and the host regulates the inflammatory response. Emerging evidence indicates that in older adults with frailty, the diversity and composition structure of gut microbiota are altered. Age-associated changes in gut microbiota composition and in their metabolites contribute to increased gut permeability and imbalances in immune function. In this review, we aim to: identify gut microbiota changes in the aging and frail populations; summarize the role of chronic low-grade inflammation in the development of frailty; and outline how gut microbiota may be related to the pathogenesis of frailty, more specifically, in the regulation of gut-derived chronic inflammation. Although additional research is needed, the regulation of gut microbiota may represent a safe, easy, and inexpensive intervention to counteract the chronic inflammation leading to frailty.

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Learning-Dependent Dendritic Spine Plasticity Is Reduced in the Aged Mouse Cortex

Frontiers in Neural Circuits ◽

10.3389/fncir.2020.581435 ◽

2020 ◽

Vol 14 ◽

Author(s):

Lianyan Huang ◽

Hang Zhou ◽

Kai Chen ◽

Xiao Chen ◽

Guang Yang

Keyword(s):

Motor Cortex ◽

Motor Learning ◽

Dendritic Spines ◽

Pyramidal Neurons ◽

Learning Ability ◽

Aged Mouse ◽

Calcium Activity ◽

Age Related ◽

Old Mice ◽

Young Mice

Aging is accompanied by a progressive decrease in learning and memory function. Synaptic loss, one of the hallmarks of normal aging, likely plays an important role in age-related cognitive decline. But little is known about the impact of advanced age on synaptic plasticity and neuronal function in vivo. In this study, we examined the structural dynamics of postsynaptic dendritic spines as well as calcium activity of layer 5 pyramidal neurons in the cerebral cortex of young and old mice. Using transcranial two-photon microscopy, we found that in both sensory and motor cortices, the elimination rates of dendritic spines were comparable between young (3–5 months) and mature adults (8–10 months), but seemed higher in old mice (>20 months), contributing to a reduction of total spine number in the old brain. During the process of motor learning, old mice compared to young mice had fewer new spines formed in the primary motor cortex. Motor training-evoked somatic calcium activity in layer 5 pyramidal neurons of the motor cortex was also lower in old than young mice, which was associated with the decline of motor learning ability during aging. Together, these results demonstrate the effects of aging on learning-dependent synapse remodeling and neuronal activity in the living cortex and suggest that synaptic deficits may contribute to age-related learning impairment.

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Effect of age on susceptibility to Salmonella Typhimurium infection in C57BL/6 mice

Journal of Medical Microbiology ◽

10.1099/jmm.0.013250-0 ◽

2009 ◽

Vol 58 (12) ◽

pp. 1559-1567 ◽

Cited By ~ 23

Author(s):

Zhihong Ren ◽

Raina Gay ◽

Adam Thomas ◽

Munkyong Pae ◽

Dayong Wu ◽

...

Keyword(s):

Immune Response ◽

Ex Vivo ◽

The Elderly ◽

Mesenteric Lymph ◽

Age Related ◽

Serovar Typhimurium ◽

Lymph Node Cells ◽

Old Mice ◽

Effect Of Age ◽

Young Mice

Ageing is associated with a decline in immune function, which predisposes the elderly to a higher incidence of infections. Information on the mechanism of the age-related increase in susceptibility to Salmonella enterica serovar Typhimurium (S. Typhimurium) is limited. In particular, little is known regarding the involvement of the immune response in this age-related change. We employed streptomycin (Sm)-pretreated C57BL/6 mice to develop a mouse model that would demonstrate age-related differences in susceptibility and immune response to S. Typhimurium. In this model, old mice inoculated orally with doses of 3×108 or 1×106 c.f.u. S. Typhimurium had significantly greater S. Typhimurium colonization in the ileum, colon, Peyer's patches, spleen and liver than young mice. Old mice had significantly higher weight loss than young mice on days 1 and 2 post-infection. In response to S. Typhimurium infection, old mice failed to increase ex vivo production of IFN-γ and TNF-α in the spleen and mesenteric lymph node cells to the same degree as observed in young mice; this was associated with their inability to maintain the presence of neutrophils and macrophages at a ‘youthful’ level. These results indicate that Sm-pretreated C57BL/6 old mice are more susceptible to S. Typhimurium infection than young mice, which might be due to impaired IFN-γ and TNF-α production as well as a corresponding change in the number of neutrophils and macrophages in response to S. Typhimurium infection compared to young mice.

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Site density of mouse intestinal glucose transporters declines with age

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1993.264.2.g285 ◽

1993 ◽

Vol 264 (2) ◽

pp. G285-G293 ◽

Cited By ~ 5

Author(s):

R. P. Ferraris ◽

J. Hsiao ◽

R. Hernandez ◽

B. Hirayama

Keyword(s):

Glucose Transporter ◽

Glucose Transporters ◽

Proximal Jejunum ◽

Site Density ◽

Phlorizin Binding ◽

Age Related ◽

Old Mice ◽

Effect Of Age ◽

Distal Jejunum ◽

Young Mice

To evaluate the effect of age on nutrient transport, the absorption rates of D-glucose, D-fructose, L-alanine, L-aspartate, L-leucine, L-lysine, L-proline, folic acid, and nicotinamide were determined in isolated jejunal tissues of young (6.7 mo old) and aged (23.7 and 27.0 mo old) mice (COBS:SFW). D-Glucose and D-fructose uptakes per milligram tissue were approximately 20-120% higher in the proximal jejunum and 15-50% higher in the distal jejunum of young mice. Amino acid and vitamin uptakes per milligram were also higher in young mice, but differences were not statistically significant. The number of Na(+)-D-glucose transporters per milligram tissue as estimated by specific phlorizin binding decreased with age. There was no age-related change in passive L-glucose permeability, in Kd of specific phlorizin binding, in transporter turnover rate, and in the molecular weight of the Na(+)-D-glucose transporter. Thus a reduction in D-glucose transporter site density fully accounts for the age-related decline in D-glucose transport rate per milligram small intestine.

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Cellular Model of Endotoxin Tolerance in Astrocytes: Role of Interleukin 10 and Oxylipins

Cells ◽

10.3390/cells8121553 ◽

2019 ◽

Vol 8 (12) ◽

pp. 1553 ◽

Cited By ~ 2

Author(s):

Dmitry V. Chistyakov ◽

Alina A. Astakhova ◽

Nadezda V. Azbukina ◽

Sergei V. Goriainov ◽

Viktor V. Chistyakov ◽

...

Keyword(s):

Inflammatory Markers ◽

Inflammatory Cytokine ◽

Endotoxin Tolerance ◽

Interleukin 10 ◽

Term Treatment ◽

Low Grade ◽

Short Term Treatment ◽

Endotoxin Challenge ◽

Protein Levels

A phenomenon of endotoxin tolerance where prior exposure of cells to minute amounts of lipopolysaccharide (LPS) causes them to become refractory to a subsequent high-amount endotoxin challenge is well described for innate immune cells such as monocytes/macrophages, but it is still obscure for brain cells. We exposed primary rat cortical astrocytes to a long-term low-grade concentration of LPS, followed by stimulation with a middle-grade concentration of LPS. Inflammatory markers, i.e., pro-inflammatory cytokine TNFα, inducible enzymes COX-2 and iNOS, anti-inflammatory cytokine interleukin 10 (IL-10) detected at the mRNA and protein levels reveal similarities between astrocytes and macrophages in the model, i.e., tolerance in pro-inflammatory markers and priming in IL-10. Long-term or short-term treatment with IL-10 does not change cell sensitivity for LPS, which makes doubtful its involvement in the mechanisms of cell tolerance development. Significant changes occur in the oxylipin profiles measured by UPLC-MS/MS analysis. The priming occurs in the following compounds: 11-HETE, PGD2, PGE2, cyclopentenone prostaglandins, and TXB2. Tolerance is observed for 12-HHT, PGF2α, and 6-keto-PGF1α. As far as we know, this is the first report on changes in oxylipin profiles in the endotoxin tolerance model. The data can greatly improve the understanding of oxylipins’ role in inflammatory and resolution processes in the brain and mechanisms of astrocyte involvement in neuroinflammation.

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