Age-dependent involvement of gut mast cells and histamine in post-stroke inflammation

Abstract Background Risk of stroke-related morbidity and mortality increases significantly with age. Aging is associated with chronic, low-grade inflammation, which is thought to contribute to the poorer outcomes after stroke seen in the elderly. Histamine (HA) is a major molecular mediator of inflammation and mast cells residing in the gut are a primary source of histamine. Methods Stroke was induced in male C57BL/6J mice at 3 months (young) and 20 months (aged) of age. Role of histamine after stroke was examined using young (Yg) and aged (Ag) mice, mice underwent MCAO surgery and were euthanized at 6h, 24h and 7 days post-ischemia; sham mice received the same surgery but no MCAO. In this work, we evaluated whether worsened outcomes after experimental stroke in aged mice was associated with age-related changes in mast cells, histamine levels, and histamine receptor expression in the gut, brain, and plasma. Results We found increased numbers of mast cells in the gut and the brain with aging. Using the middle cerebral artery occlusion (MCAO) model of ischemic stroke, we demonstrate that stroke leads to increased numbers of mast cells and histamine receptors in the gut. These gut-centric changes are associated with elevated levels of HA and other pro-inflammatory cytokines including IL-6, G-CSF, TNF-α, and IFN-γ in the peripheral circulation. Our data also shows that post-stroke gut inflammation led to a significant reduction of mucin-producing goblet cells and a loss of gut barrier integrity. Lastly, gut inflammation after stroke is associated with changes in the composition of the gut microbiota as early as 24 hours post-stroke. Conclusion An important theme emerging from our results is that acute inflammatory events following ischemic insults in the brain persist longer in the aged mice when compared to younger animals. Taken together, our findings implicate mast cell activation and histamine signaling as a part of peripheral inflammatory response after ischemic stroke, which are profound in aged animals. Interfering with histamine signaling orally might provide translational value to improve stroke outcome.

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Age-dependent involvement of gut mast cells and histamine in post-stroke inflammation

10.21203/rs.2.21718/v2 ◽

2020 ◽

Author(s):

Maria Pilar Blasco ◽

Anjali Chauhan ◽

Pedram Honarpisheh ◽

Hilda Ahnstedt ◽

John d’Aigle ◽

...

Keyword(s):

Ischemic Stroke ◽

Mast Cells ◽

Receptor Expression ◽

Mast Cell Activation ◽

Low Grade ◽

Gut Inflammation ◽

Aged Mice ◽

Post Stroke ◽

Age Related ◽

The Brain

Abstract Background Risk of stroke-related morbidity and mortality increases significantly with age. Aging is associated with chronic, low-grade inflammation, which is thought to contribute to the poorer outcomes after stroke seen in the elderly. Histamine (HA) is a major molecular mediator of inflammation and mast cells residing in the gut are a primary source of histamine. Methods Stroke was induced in male C57BL/6J mice at 3 months (young) and 20 months (aged) of age. Role of histamine after stroke was examined using young (Yg) and aged (Ag) mice, mice underwent MCAO surgery and were euthanized at 6h, 24h and 7 days post-ischemia; sham mice received the same surgery but no MCAO. In this work, we evaluated whether worsened outcomes after experimental stroke in aged mice was associated with age-related changes in mast cells, histamine levels, and histamine receptor expression in the gut, brain, and plasma. Results We found increased numbers of mast cells in the gut and the brain with aging. Using the middle cerebral artery occlusion (MCAO) model of ischemic stroke, we demonstrate that stroke leads to increased numbers of mast cells and histamine receptors in the gut. These gut-centric changes are associated with elevated levels of HA and other pro-inflammatory cytokines including IL-6, G-CSF, TNF-α, and IFN-γ in the peripheral circulation. Our data also shows that post-stroke gut inflammation led to a significant reduction of mucin-producing goblet cells and a loss of gut barrier integrity. Lastly, gut inflammation after stroke is associated with changes in the composition of the gut microbiota as early as 24 hours post-stroke. Conclusion An important theme emerging from our results is that acute inflammatory events following ischemic insults in the brain persist longer in the aged mice when compared to younger animals. Taken together, our findings implicate mast cell activation and histamine signaling as a part of peripheral inflammatory response after ischemic stroke, which are profound in aged animals. Interfering with histamine signaling orally might provide translational value to improve stroke outcome.

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Brain mast cells link the immune system to anxiety-like behavior

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.0809479105 ◽

2008 ◽

Vol 105 (46) ◽

pp. 18053-18057 ◽

Cited By ~ 108

Author(s):

Katherine M. Nautiyal ◽

Ana C. Ribeiro ◽

Donald W. Pfaff ◽

Rae Silver

Keyword(s):

Mast Cell ◽

Mast Cells ◽

Cell Activation ◽

Mast Cell Activation ◽

Neural Systems ◽

Loss Of Function ◽

Littermate Control ◽

Cytokines And Chemokines ◽

Function Models ◽

The Brain

Mast cells are resident in the brain and contain numerous mediators, including neurotransmitters, cytokines, and chemokines, that are released in response to a variety of natural and pharmacological triggers. The number of mast cells in the brain fluctuates with stress and various behavioral and endocrine states. These properties suggest that mast cells are poised to influence neural systems underlying behavior. Using genetic and pharmacological loss-of-function models we performed a behavioral screen for arousal responses including emotionality, locomotor, and sensory components. We found that mast cell deficient KitW−sh/W−sh (sash−/−) mice had a greater anxiety-like phenotype than WT and heterozygote littermate control animals in the open field arena and elevated plus maze. Second, we show that blockade of brain, but not peripheral, mast cell activation increased anxiety-like behavior. Taken together, the data implicate brain mast cells in the modulation of anxiety-like behavior and provide evidence for the behavioral importance of neuroimmune links.

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Abstract TP274: Orosomucoid-1 Protein Increases Following Ischemic Stroke in the Brain and Periphery

Stroke ◽

10.1161/str.47.suppl_1.tp274 ◽

2016 ◽

Vol 47 (suppl_1) ◽

Author(s):

Hetal Mistry ◽

Madeline Levy ◽

Meaghan Roy-O'Reilly ◽

Louise McCullough

Keyword(s):

Sex Differences ◽

Ischemic Stroke ◽

Rna Sequencing ◽

Multiple Testing ◽

Enzyme Linked Immunosorbent Assay ◽

Mrna Levels ◽

Stroke Patients ◽

Post Stroke ◽

Protein Levels ◽

The Brain

Background and Purpose: Orosomucoid-1 (ORM-1) is an abundant protein with important roles in inflammation and immunosuppression. We utilized RNA sequencing to measure mRNA levels in human ischemic stroke patients, with confirmation by serum ORM-1 protein measurements. A mouse model of ischemic stroke was then used to examine post-stroke changes in ORM-1 within the brain itself. Hypothesis: We tested the hypothesis that ORM-1 levels increase following ischemic stroke, with sex differences in protein dynamics over time. Methods: RNA sequencing was performed on whole blood from ischemic stroke patients (n=23) and controls (n=12), with Benjamini-Hochberg correction for multiple testing. Enzyme-linked immunosorbent assay was performed on serum from ischemic stroke patients (n=28) and controls (n=8), with analysis by T-test. For brain analysis, mice (n=14) were subjected to a 90-minute middle cerebral artery occlusion (MCAO) surgery and sacrificed 6 or 24 hours after stroke. Control mice underwent parallel “sham” surgery without occlusion. Western blotting was used to detect ORM-1 protein levels in whole brain, with analysis by two-way ANOVA. Results: RNA sequencing showed a 2.8-fold increase in human ORM-1 at 24 hours post-stroke (q=.0029), an increase also seen in serum ORM-1 protein levels (p=.011). Western blot analysis of mouse brain revealed that glycosylated (p=0.0003) and naive (p=0.0333) forms of ORM-1 were higher in female mice compared to males 6 hours post-stroke. Interestingly, ORM-1 levels were higher in the brains of stroke mice at 6 hours (p=.0483), while at 24 hours ORM-1 levels in stroke mice were lower than their sham counterparts (p=.0212). In both human and mouse data, no sex differences were seen in ORM-1 levels in the brain or periphery at 24 hours post-stroke. Conclusion: In conclusion, ORM-1 is a sexually dimorphic protein involved in the early (<24 hour) response to ischemic stroke. This research serves as an initial step in determining the mechanism of ORM-1 in the ischemic stroke response and its potential as a future therapeutic target for both sexes.

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Abstract TP111: Activation of the Brain Renin-Angiotensin System by Translational Approaches Following Stroke Onset Is Neuroprotective in a Rat Model of Ischemic Stroke

Stroke ◽

10.1161/str.44.suppl_1.atp111 ◽

2013 ◽

Vol 44 (suppl_1) ◽

Author(s):

Douglas M Bennion ◽

Lauren Donnangelo ◽

David Pioquinto ◽

Robert Regenhardt ◽

Mohan K Raizada ◽

...

Keyword(s):

Ischemic Stroke ◽

Infarct Volume ◽

Renin Angiotensin System ◽

Cerebral Infarct ◽

Intraventricular Administration ◽

Angiotensin System ◽

Renin Angiotensin ◽

Post Stroke ◽

Neurologic Deficits ◽

The Brain

Background: Toward discovering novel stroke therapies, recent research has shown that activation of the newly-discovered angiotensin converting enzyme 2/angiotensin-(1-7)/mas (ACE2/Ang-(1-7)/Mas) pathway, a counter-regulatory axis of the brain renin-angiotensin system, is neuroprotective in ischemic stroke in rats. Specifically, intraventricular administration of the novel ACE2 activator diminazine aceturate (DIZE) before and during an ischemic stroke decreases cerebral infarct and neurologic deficits. Efficacy must now be demonstrated using minimally-invasive methods if this therapy is to be translated to the care of human patients. In this study, we assessed the hypothesis that systemic administration of DIZE post ischemic stroke would be neuroprotective. Methods: Adult male Sprague-Dawley rats underwent ischemic stroke by endothelin-1 induced middle cerebral artery occlusion and were randomly divided into 2 groups (n=9-10/set): 1) intraperitoneal (IP) administrations of DIZE (7.5 mg/kg) at 4, 24, and 48 h after stroke; 2) IP administrations of 0.9% saline vehicle at the same time points. At 24 and 72 h after stroke, rats underwent blinded neurologic assessments. Immediately following the 72 h tests, animals were sacrificed, cerebral infarct volumes assessed by TTC staining, and IL-1β expression in the stroke region analyzed by rt-PCR. Data are expressed as mean ± SEM with significance inferred at p<0.05. Results: Mean infarct volume was significantly decreased by IP injections of DIZE (9.4% ± 4.35) as compared to control (22.8%±3.6, p=0.039). At 24 h post stroke, neurologic deficits (Garcia Scale) were significantly improved in the DIZE treated group (16.7±0.40) versus the saline group (15.22±0.57, p=0.037). Although DIZE tended to improve neurologic deficits 72 h post stroke, this trend was not significant. Finally, DIZE treatment significantly reduced mRNA expression of IL-1β (0.43 ± 0.14) in the cerebral cortical stroke region as compared to saline treatment (1.47±0.08, p=0.001). Conclusions: Our findings suggest that targeting the ACE2/Ang-(1-7)/Mas axis post stroke can improve function, decrease inflammation, and reduce infarct volume - a significant translational step in brain renin-angiotensin system research.

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Abstract WMP45: Manipulation of the Microbiome Improves Functional Recovery After Ischemic Stroke

Stroke ◽

10.1161/str.47.suppl_1.wmp45 ◽

2016 ◽

Vol 47 (suppl_1) ◽

Author(s):

Michal Jandzinski ◽

Venugopal Venna ◽

Anjali Chauhan ◽

Joerg Graf ◽

Louise D McCullough

Keyword(s):

Functional Recovery ◽

Artery Occlusion ◽

Peripheral Tissues ◽

Aged Mice ◽

Age Related ◽

Y Maze ◽

Obesity Hypertension ◽

Inflammatory Milieu ◽

Gastro Intestinal Tract ◽

The Brain

Background: Circulating inflammatory markers increase with age. This pro-inflammatory milieu makes the organism less capable of coping with stressors such as stroke. Age related inflammation occurs in both the brain and peripheral tissues like the gastro-intestinal tract. There is increasing recognition that commensal bacteria in the GI tract are altered with age or with germ-free housing, affecting the brain. The change occurs most notably in the ratio of two major phyla of the microbiome, the Firmicutes and Bacteroidetes . Young age is associated with a low ratio of the two but this ratio increases with age, which has been linked to many diseases including obesity, hypertension, and diabetes which are major risk factors for stroke. Hypothesis: We hypothesized that there would be age-related differences in the microbiome, and that restoration of a young microbiome would improve functional recovery in aged mice. Methods: Fecal transplants from young and aged donors were administered to recipient animals after suppression of endogenous microbial compositions through concentrated Streptomycin. This allowed for successful colonization of the gut with the newly transplanted microbiome. A transient middle cerebral artery occlusion (MCAO) was used in young (3-4 month) and aged (18-20 month) male mice 4 weeks after transplant. Functional recovery was assessed by neurological deficit scores, the hang wire test, and open field activity. The Y-maze was used to assess cognitive impairment. Results: We successfully reversed the microbiomes of aged organisms and gave young animals “aged” biomes. Animals with “aged” microbiomes prior to stroke had worsened functional recovery based on all behavioral tests. The “aged” biome increased mortality rates most notably in the young recipients which had over 50% mortality. Aged mice had significantly improved functional recovery as assessed by the HW test ( P < 0.05 ) and NDS after reconstitution of “young” microbiome prior to stroke compared to aged control animals with the normal “aged” microbiomes. Conclusion: Aged mice have high Firmicutes and Bacteroidetes relative abundances. Manipulation of the microbiome in young and aged mice is possible. Restoration of a youthful biome improved functional recovery in aged mice.

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Beyond IgE: Alternative Mast Cell Activation Across Different Disease States

International Journal of Molecular Sciences ◽

10.3390/ijms21041498 ◽

2020 ◽

Vol 21 (4) ◽

pp. 1498 ◽

Cited By ~ 7

Author(s):

David O. Lyons ◽

Nicholas A. Pullen

Keyword(s):

Mast Cell ◽

Mast Cells ◽

Cell Activation ◽

Autoimmune Disorders ◽

Receptor Expression ◽

Mast Cell Activation ◽

Food Allergies ◽

Type I ◽

Disease States ◽

Ige Mediated

Mast cells are often regarded through the lens of IgE-dependent reactions as a cell specialized only for anti-parasitic and type I hypersensitive responses. However, recently many researchers have begun to appreciate the expansive repertoire of stimuli that mast cells can respond to. After the characterization of the interleukin (IL)-33/suppression of tumorigenicity 2 (ST2) axis of mast cell activation—a pathway that is independent of the adaptive immune system—researchers are revisiting other stimuli to induce mast cell activation and/or subsequent degranulation independent of IgE. This discovery also underscores that mast cells act as important mediators in maintaining body wide homeostasis, especially through barrier defense, and can thus be the source of disease as well. Particularly in the gut, inflammatory bowel diseases (Crohn’s disease, ulcerative colitis, etc.) are characterized with enhanced mast cell activity in the context of autoimmune disease. Mast cells show phenotypic differences based on tissue residency, which could manifest as different receptor expression profiles, allowing for unique mast cell responses (both IgE and non-IgE mediated) across varying tissues as well. This variety in receptor expression suggests mast cells respond differently, such as in the gut where immunosuppressive IL-10 stimulates the development of food allergy or in the lungs where transforming growth factor-β1 (TGF-β1) can enhance mast cell IL-6 production. Such differences in receptor expression illustrate the truly diverse effector capabilities of mast cells, and careful consideration must be given toward the phenotype of mast cells observed in vitro. Given mast cells’ ubiquitous tissue presence and their capability to respond to a broad spectrum of non-IgE stimuli, it is expected that mast cells may also contribute to the progression of autoimmune disorders and other disease states such as metastatic cancer through promoting chronic inflammation in the local tissue microenvironment and ultimately polarizing toward a unique Th17 immune response. Furthermore, these interconnected, atypical activation pathways may crosstalk with IgE-mediated signaling differently across disorders such as parasitism, food allergies, and autoimmune disorders of the gut. In this review, we summarize recent research into familiar and novel pathways of mast cells activation and draw connections to clinical human disease.

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Aging and serum MCP-1 are associated with gut microbiome composition in a murine model

10.7287/peerj.preprints.1754v1 ◽

2016 ◽

Author(s):

Melissa N. Conley ◽

Carmen P. Wong ◽

Kyle M. Duyck ◽

Norman Hord ◽

Emily Ho ◽

...

Keyword(s):

Immune System ◽

Murine Model ◽

Gut Microbiome ◽

Inflammatory Marker ◽

Low Grade ◽

Host Immune System ◽

Cancer Type ◽

Microbiome Composition ◽

Aged Mice ◽

Age Related

Introduction Age is the primary risk factor for major human chronic diseases, including cardiovascular disorders, cancer, type 2 diabetes, and neurodegenerative diseases. Chronic, low-grade, systemic inflammation is associated with aging and the progression of immunosenescence. Immunosenescence may play an important role in the development of age-related chronic disease and the widely observed phenomenon of increased production of inflammatory mediators that accompany this process, referred to as “inflammaging”. While it has been demonstrated that the gut microbiome and immune system interact, the relationship between the gut microbiome and age remains to be clearly defined, particularly in the context of inflammation. The aim of the study was to clarify the associations between age, the gut microbiome, and pro-inflammatory marker serum MCP-1 in a C57BL/6 murine model. Results We used 16S rRNA gene sequencing to profile the composition of fecal microbiota associated with young and aged mice. Our analysis identified an association between microbiome structure and mouse age, and revealed specific groups of taxa whose abundances stratify young and aged mice. This includes the Ruminococcaceae, Clostridiaceae, and Enterobacteriaceae. We also profiled pro-inflammatory serum MCP-1 levels of each mouse and found that aged mice exhibited elevated serum MCP-1, a phenotype consistent with inflammaging. Robust correlation tests identified several taxa whose abundance in the microbiome associates with serum MCP-1 status, indicating that they may interact with the mouse immune system. We find that taxonomically similar organisms can exhibit differing, even opposite, patterns of association with the host immune system. We also find that many of the OTUs that associate with serum MCP-1 also stratify individuals by age. Discussion Our results demonstrate that gut microbiome composition is associated with age and the pro-inflammatory marker, serum MCP-1. The correlation between age, relative abundance of specific taxa in the gut microbiome, and serum MCP-1 status in mice indicates that the gut microbiome may play a modulating role in age-related inflammatory processes. These findings warrant further investigation of taxa associated with the inflammaging phenotype and the role of gut microbiome in the health status and immune function of aged individuals.

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A Walnut-Enriched Diet Modifies the Oxylipin Profile in Liver and Brain of Aged Mice — Impact on Inflammation Markers

Current Developments in Nutrition ◽

10.1093/cdn/nzaa057_019 ◽

2020 ◽

Vol 4 (Supplement_2) ◽

pp. 1203-1203

Author(s):

Gunter Eckert ◽

Gunter Esselun ◽

Elisabeth Koch ◽

Nils Schebb

Keyword(s):

Physical Activity ◽

Fatty Acids ◽

Brain Aging ◽

Inflammatory Marker ◽

Inflammation Markers ◽

Aged Mice ◽

Funding Sources ◽

Age Related ◽

The Brain ◽

Related Increase

Abstract Objectives Neuroinflammation contributes to brain-aging which may be mitigated by anti-inflammatory oxylipins. Based on our previous findings that a 6% walnut-enriched diet alone, and additional physical activity (PA), enhanced cognition in 18 months old NMRI, we now investigated the effects of this diet on oxylipin- and inflammatory marker levels in liver and brain. Methods 18 months and 3 months old female NMRI mice were fed with a 6% walnut-enriched diet. Oxylipins were determined in brain and liver sections using LC-MS. Expression of IL1β gene was determined by qRT-PCR. Results The walnut diet compensates for the age related increase in IL1β gene expression in the liver of mice, whereas expression in the brain was not affected. Basal levels of oxylipins in brain and liver samples isolated from young mice were generally lower compared to aged mice. The walnut diet further increased oxylipin levels of walnut specific fatty acids in liver and brain of aged mice. Enrichment of linoleic acid (LA) and α-linolenic acid (ALA) derived oxylipin levels were quantitatively higher in the liver compared to the brain (P < 0.0001). Hydroxy-oxylipins (HO) based on fatty acid LA were significantly increased in brain (P < 0.001) and liver (P < 0.0001) compared to control mice, while ALA based HO were only detected in the brains of walnut fed mice. The walnut diet in combination with physical activity (PA) reduced ARA based oxylipin levels (P < 0.05). Across all groups, concentrations of prostanoids were higher in the brain as compared to liver (P < 0.001). In the liver, walnuts tended to decrease PGD2 and TxB2 levels while increasing 6-keto PGF1α. The latter, as well as TxB2 tended to be decreased in the brain. Other ARA based prostanoids were unaffected. Effects of PA were contrary to each other, tending to increase ARA based prostanoids in the liver while decreasing them in the brain. PA further enhanced this effect in the brain, but tended to increase the inflammatory response in the liver. Conclusions A walnut diet differentially affects the oxylipin profile of liver and brain in aged mice. Production of oxylipins based on walnut fatty acids is generally increased. Attenuation of age-related, chronic inflammation in might be one of walnut's benefits and may contribute to a healthier aging of the brain. Funding Sources Research was supported by grants from California Walnut Commission.

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Hazelnut modulates neurobehaviour and ameliorates ageing-induced oxidative stress, and caspase-3-mediated apoptosis in mice

Current Aging Science ◽

10.2174/1874609813666201228112349 ◽

2020 ◽

Vol 13 ◽

Author(s):

Anthony Tope Olofinnade ◽

Adejoke Yetunde Onaolapo ◽

Olakunle James Onaolapo ◽

Olugbenga Adekunle Olowe

Keyword(s):

Weight Gain ◽

Caspase 3 ◽

Standard Diet ◽

Dopamine Level ◽

Biochemical Tests ◽

Aged Mice ◽

Beneficial Effects ◽

Body Tissues ◽

Age Related ◽

The Brain

Background: Organismal aging has been associated with deleterious effects in different body tissues and organs, including the brain. There have been reports from ancient medicinal scripts of the beneficial effects of nuts like hazelnut in preventing aging induced-brain atrophy and memory loss. Objectives: This study examined the potential beneficial effects of a diet supplemented with two different (Italian and Turkish) cultivars of hazelnut on the brain of aged mice. Methods: Aged (24 months old) mice were randomly assigned into 7 groups of ten mice each. Mice were grouped as standard diet (SD) control, three groups of Turkish and three groups of Italian hazelnut incorporated into SD at 2, 4 and 8% respectively. Animals were fed standard or hazelnut diet for 8 weeks. On day 56, behaviours in the elevated plus maze, radial-arm maze, open field, and Y-maze paradigms were monitored and scored, following which animals were euthanized. The brains were removed, weighed and homogenized for the assessment of specific biochemical tests. Result: Results showed that hazelnut-supplemented diet was associated with significantly increased weight gain, with the Italian hazelnut being associated with greater weight gain. Hazelnut-supplemented diet also increased behavioural parameters such as horizontal locomotion and grooming, while it decreased rearing activity. Working-memory also improved significantly with both cultivars of hazelnut, while anxiety indices were reduced at lower concentrations of Italian, and higher concentrations of Turkish hazelnut. Both hazelnut varieties were associated with reduction in acetylcholinesterase activity, reduction in superoxide dismutase activity, reduction in nitric oxide levels, reduction in caspase-3 level, but increased dopamine level. Conclusion: Overall hazelnut cultivars have beneficial effects on the brain in aged mice; suggesting a possible role in the prevention or management of age-related neurodegenerative changes.

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