scholarly journals Macrophage LC3-associated phagocytosis is an immune defense against Streptococcus pneumoniae that diminishes with host aging

2020 ◽  
Vol 117 (52) ◽  
pp. 33561-33569
Author(s):  
Megumi Inomata ◽  
Shuying Xu ◽  
Pallavi Chandra ◽  
Simin N. Meydani ◽  
Genzou Takemura ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Inflammatory Responses ◽  
The Elderly ◽  
Invasive Disease ◽  
Immune Defense ◽  
Bacterial Killing ◽  
Murine Bone Marrow ◽  
Aged Mice ◽  
Age Related ◽  
Old Mice

Streptococcus pneumoniae is a leading cause of pneumonia and invasive disease, particularly, in the elderly. S. pneumoniae lung infection of aged mice is associated with high bacterial burdens and detrimental inflammatory responses. Macrophages can clear microorganisms and modulate inflammation through two distinct lysosomal trafficking pathways that involve 1A/1B-light chain 3 (LC3)-marked organelles, canonical autophagy, and LC3-associated phagocytosis (LAP). The S. pneumoniae pore-forming toxin pneumolysin (PLY) triggers an autophagic response in nonphagocytic cells, but the role of LAP in macrophage defense against S. pneumoniae or in age-related susceptibility to infection is unexplored. We found that infection of murine bone-marrow-derived macrophages (BMDMs) by PLY-producing S. pneumoniae triggered Atg5- and Atg7-dependent recruitment of LC3 to S. pneumoniae-containing vesicles. The association of LC3 with S. pneumoniae-containing phagosomes required components specific for LAP, such as Rubicon and the NADPH oxidase, but not factors, such as Ulk1, FIP200, or Atg14, required specifically for canonical autophagy. In addition, S. pneumoniae was sequestered within single-membrane compartments indicative of LAP. Importantly, compared to BMDMs from young (2-mo-old) mice, BMDMs from aged (20- to 22-mo-old) mice infected with S. pneumoniae were not only deficient in LAP and bacterial killing, but also produced higher levels of proinflammatory cytokines. Inhibition of LAP enhanced S. pneumoniae survival and cytokine responses in BMDMs from young but not aged mice. Thus, LAP is an important innate immune defense employed by BMDMs to control S. pneumoniae infection and concomitant inflammation, one that diminishes with age and may contribute to age-related susceptibility to this important pathogen.

scholarly journals AMPK activates Parkin independent autophagy and improves post sepsis immune defense against secondary bacterial lung infections

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nathaniel B. Bone ◽  
Eugene J. Becker ◽  
Maroof Husain ◽  
Shaoning Jiang ◽  
Anna A. Zmijewska ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Pathogenic Bacteria ◽  
Inflammatory Responses ◽  
Abdominal Sepsis ◽  
Immune Defense ◽  
Bacterial Killing ◽  
Lung Infections ◽  
Sepsis Survivors ◽  
The Impact

AbstractMetabolic and bioenergetic plasticity of immune cells is essential for optimal responses to bacterial infections. AMPK and Parkin ubiquitin ligase are known to regulate mitochondrial quality control mitophagy that prevents unwanted inflammatory responses. However, it is not known if this evolutionarily conserved mechanism has been coopted by the host immune defense to eradicate bacterial pathogens and influence post-sepsis immunosuppression. Parkin, AMPK levels, and the effects of AMPK activators were investigated in human leukocytes from sepsis survivors as well as wild type and Park2−/− murine macrophages. In vivo, the impact of AMPK and Parkin was determined in mice subjected to polymicrobial intra-abdominal sepsis and secondary lung bacterial infections. Mice were treated with metformin during established immunosuppression. We showed that bacteria and mitochondria share mechanisms of autophagic killing/clearance triggered by sentinel events that involve depolarization of mitochondria and recruitment of Parkin in macrophages. Parkin-deficient mice/macrophages fail to form phagolysosomes and kill bacteria. This impairment of host defense is seen in the context of sepsis-induced immunosuppression with decreased levels of Parkin. AMPK activators, including metformin, stimulate Parkin-independent autophagy and bacterial killing in leukocytes from post-shock patients and in lungs of sepsis-immunosuppressed mice. Our results support a dual role of Parkin and AMPK in the clearance of dysfunctional mitochondria and killing of pathogenic bacteria, and explain the immunosuppressive phenotype associated Parkin and AMPK deficiency. AMPK activation appeared to be a crucial therapeutic target for the macrophage immunosuppressive phenotype and to reduce severity of secondary bacterial lung infections and respiratory failure.

Link between aging and atheroprotection in Mif-deficient atherosclerotic mice

2021 ◽  
Author(s):  
Christine Maria Krammer ◽  
Bishan Yang ◽  
Sabrina Reichl ◽  
Verena Bolini ◽  
Corinna Schulte ◽  
...  
Keyword(s):  
Atherogenic Diet ◽  
Cell Recruitment ◽  
Aged Mice ◽  
Cell Responses ◽  
Gene Deficiency ◽  
Cytokines And Chemokines ◽  
Age Related ◽  
Chronic Inflammatory Condition ◽  
Antibody Levels ◽  
Old Mice

Atherosclerosis is a lipid-triggered chronic inflammatory condition of our arteries and the main underlying pathology of myocardial infarction and stroke. Pathogenesis is age-dependent, but the mechanistic links between disease progression, age, and atherogenic cytokines and chemokines are incompletely understood. Here, we studied the chemokine-like inflammatory cytokine macrophage migration inhibitory factor (MIF) in atherogenic Apoe-/- mice across different stages of aging and cholesterol-rich high-fat diet (HFD). MIF promotes atherosclerosis by mediating atherogenic monocyte and T-cell recruitment, amplifying lesional inflammation, and suppressing atheroprotective B-cell responses. However, age-related links between atherogenesis and MIF and its role in advanced atherosclerosis in aged mice have not been systematically explored. We compared effects of global Mif-gene deficiency in 30-, 42-, and 48-week-old Apoe-/- mice on HFD for 24, 36, or 42 weeks, respectively, and in 52-week-old mice on a 6-week HFD. While a regio-specific atheroprotective phenotype of Mif-deficiency was observed in the 30/24-week-old group, atheroprotection was not detected in the 48/42- and 52/6-week-old groups, suggesting that atheroprotection afforded by global Mif-gene deletion differs across aging stages and atherogenic diet duration. We identify a combination of mechanisms that could explain this phenotype: i) Mif-deficiency promotes lesional Trem2+ macrophage numbers in younger but not aged mice; ii) Mif-deficiency favors formation of lymphocyte-rich stage-I/II ATLOs in younger mice but ATLO numbers equalize with those in Apoe-/- controls in the older mice; and iii) plasma anti-oxLDL-IgM antibody levels are decreased in aged Mif-deficient mice. Of note, these three markers (Trem2+ macrophages, ATLOs, anti-oxLDL-IgM antibodies) have been previously linked to atheroprotection. Together, our study thus suggests that regio-specific atheroprotection due to global Mif-gene deficiency in atherogenic Apoe-/- mice is lost upon advanced aging and identifies mechanisms that could explain this phenotype shift. These observations may have implications for translational MIF-directed strategies.

Abstract 65: Restoration of Growth Differentiation Factor 11 Protects Against Stroke in Mice

Stroke ◽  
2016 ◽  
Vol 47 (suppl_1) ◽  
Author(s):  
Anjali Chauhan ◽  
Jacob Hudobenko ◽  
Anthony Patrizz ◽  
Louise D McCullough
Keyword(s):  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
The Elderly ◽  
Vehicle Group ◽  
Peripheral Tissues ◽  
Delayed Treatment ◽  
Aged Mice ◽  
Infarct Area ◽  
Age Related

Introduction: GDF 11 is a member of the transforming growth factor β superfamily. Loss of GDF11 occurs with aging and declining levels correlate with several detrimental age-associated phenotypes in both peripheral tissues and brain. Restoration of GDF11 enhances neurogenesis and cognitive function in aged mice. Brain expression of GDF11 has not been investigated after stroke. Stroke differentially affects the elderly. In this work we examined the role of GDF11 in aging, stroke and its potential utility as a neuroprotective agent. Methods: Male C57/BL6NCrl young (2-3 months) and aged (19-21) mice were used. Brain GDF11 expression was evaluated in young and aged mice by western blot. Focal ischemia was induced with a transient middle cerebral artery occlusion (MCAO). Mice were randomly assigned into two groups and were subjected to 90 min MCAO. Group 1 received vehicle (phosphate buffered saline) and group 2 was administered rGDF11 (100 ug/kg., ip) at the onset of ischemia. In additional experiments, the efficacy of delayed treatment (3 h after ischemia) with rGDF11 was tested. These mice were subjected to a 60 min MCAO. Mice were euthanized after 24 hours and 7 days respectively and brains were harvested to estimate infarct area. Results: A significant decrease in brain GDF11 levels was observed in aged mice as compared to young (p<0.05). Additionally, a significant decline in brain GDF11 expression was observed after stroke at 24 hours vs. sham groups (p<0.05). A significant decrease in cortical and hemispheric infarct area was observed in the rGDF11 group (cortical 48.73±1.05; hemisphere 49.68±3.58) as compared to vehicle group (60.54±4.88; 61.35±6.03), when GDF was administered at the time of ischemia. Delayed treatment with rGDF11 also reduced infarct at 7 days. Conclusions: Brain GDF11 levels decline with age and after stroke. Supplementation with rGDF11 ameliorates stroke induced injury in young mice at 24h and 7 days. These finding suggest potential role of GDF11 in age and stroke. Restoration of age-related loss of GDF may be a viable therapy for stroke.

scholarly journals Neuroinflammation in Aged Brain: Impact of the Oral Administration of Ellagic Acid Microdispersion

2020 ◽  
Vol 21 (10) ◽  
pp. 3631 ◽  
Author(s):  
Raffaella Boggia ◽  
Federica Turrini ◽  
Alessandra Roggeri ◽  
Guendalina Olivero ◽  
Francesca Cisani ◽  
...  
Keyword(s):  
Oral Administration ◽  
Ellagic Acid ◽  
Ex Vivo ◽  
Behavioral Skills ◽  
Aged Mice ◽  
Age Related ◽  
The Central Nervous System ◽  
The Impact ◽  
Old Mice

The immune system and the central nervous system message each other to preserving central homeostasis. Both systems undergo changes during aging that determine central age-related defects. Ellagic acid (EA) is a natural product which is beneficial in both peripheral and central diseases, including aging. We analyzed the impact of the oral administration of a new oral ellagic acid micro-dispersion (EAm), that largely increased the EA solubility, in young and old mice. Oral EAm did not modify animal weight and behavioral skills in young and old mice, but significantly recovered changes in “ex-vivo, in vitro” parameters in old animals. Cortical noradrenaline exocytosis decreased in aged mice. EAm administration did not modify noradrenaline overflow in young animals, but recovered it in old mice. Furthermore, GFAP staining was increased in the cortex of aged mice, while IBA-1 and CD45 immunopositivities were unchanged when compared to young ones. EAm treatment significantly reduced CD45 signal in both young and old cortical lysates; it diminished GFAP immunopositivity in young mice, but failed to affect IBA-1 expression in both young and old animals. Finally, EAm treatment significantly reduced IL1beta expression in old mice. These results suggest that EAm is beneficial to aging and represents a nutraceutical ingredient for elders.

scholarly journals Stroke Induces a BDNF-Dependent Improvement in Cognitive Flexibility in Aged Mice

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Josh Houlton ◽  
Lisa Y. Y. Zhou ◽  
Deanna Barwick ◽  
Emma K. Gowing ◽  
Andrew N. Clarkson
Keyword(s):  
Animal Model ◽  
Cognitive Flexibility ◽  
Cognitive Deficits ◽  
Cox Regression ◽  
Reversal Task ◽  
Critical Window ◽  
Aged Mice ◽  
Sham Surgery ◽  
Age Related ◽  
Old Mice

Stroke remains a leading cause of disability worldwide. Recently, we have established an animal model of stroke that results in delayed impairment in spatial memory, allowing us to better investigate cognitive deficits. Young and aged brains show different recovery profiles after stroke; therefore, we assessed aged-related differences in poststroke cognition. As neurotrophic support diminishes with age, we also investigated the involvement of brain-derived neurotrophic factor (BDNF) in these differences. Young (3-6 months old) and aged (16-21 months old) mice were trained in operant touchscreen chambers to complete a visual pairwise discrimination (VD) task. Stroke or sham surgery was induced using the photothrombotic model to induce a bilateral prefrontal cortex stroke. Five days poststroke, an additional cohort of aged stroke animals were treated with intracerebral hydrogels loaded with the BDNF decoy, TrkB-Fc. Following treatment, animals underwent the reversal and rereversal task to identify stroke-induced cognitive deficits at days 17 and 37 poststroke, respectively. Assessment of sham animals using Cox regression and log-rank analyses showed aged mice exhibit an increased impairment on VD reversal and rereversal learning compared to young controls. Stroke to young mice revealed no impairment on either task. In contrast, stroke to aged mice facilitated a significant improvement in reversal learning, which was dampened in the presence of the BDNF decoy, TrkB-Fc. In addition, aged stroke control animals required significantly less consecutive days and correction trials to master the reversal task, relative to aged shams, an effect dampened by TrkB-Fc. Our findings support age-related differences in recovery of cognitive function after stroke. Interestingly, aged stroke animals outperformed their sham counterparts, suggesting reopening of a critical window for recovery that is being mediated by BDNF.

scholarly journals Age-related exacerbation of hematopoietic organ damage induced by systemic hyper-inflammation in senescence-accelerated mice

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tomonori Harada ◽  
Isao Tsuboi ◽  
Hirotsugu Hino ◽  
Miyuki Yuda ◽  
Yoko Hirabayashi ◽  
...  
Keyword(s):  
Stromal Cells ◽  
The Elderly ◽  
Organ Damage ◽  
Hematopoietic Organ ◽  
Aged Mice ◽  
Gm Csf ◽  
Expression Of Genes ◽  
Age Related ◽  
Genes Encoding ◽  
Positive Regulators

AbstractHemophagocytic lymphohistiocytosis (HLH) is a life-threatening systemic hyper-inflammatory disorder. The mortality of HLH is higher in the elderly than in young adults. Senescence-accelerated mice (SAMP1/TA-1) exhibit characteristic accelerated aging after 30 weeks of age, and HLH-like features, including hematopoietic organ damage, are seen after lipopolysaccharide (LPS) treatment. Thus, SAMP1/TA-1 is a useful model of hematological pathophysiology in the elderly with HLH. In this study, dosing of SAMP1/TA-1 mice with LPS revealed that the suppression of myelopoiesis and B-lymphopoiesis was more severe in aged mice than in young mice. The bone marrow (BM) expression of genes encoding positive regulators of myelopoiesis (G-CSF, GM-CSF, and IL-6) and of those encoding negative regulators of B cell lymphopoiesis (TNF-α) increased in both groups, while the expression of genes encoding positive-regulators of B cell lymphopoiesis (IL-7, SDF-1, and SCF) decreased. The expression of the GM-CSF-encoding transcript was lower in aged mice than in young animals. The production of GM-CSF by cultured stromal cells after LPS treatment was also lower in aged mice than in young mice. The accumulation of the TNF-α-encoding transcript and the depletion of the IL-7-encoding transcript were prolonged in aged mice compared to young animals. LPS dosing led to a prolonged increase in the proportion of BM M1 macrophages in aged mice compared to young animals. The expression of the gene encoding p16INK4a and the proportion of β-galactosidase- and phosphorylated ribosomal protein S6-positive cells were increased in cultured stromal cells from aged mice compared to those from young animals, while the proportion of Ki67-positive cells was decreased in stromal cells from aged mice. Thus, age-related deterioration of stromal cells probably causes the suppression of hematopoiesis in aged mice. This age-related latent organ dysfunction may be exacerbated in elderly people with HLH, resulting in poor prognosis.

scholarly journals Senolytics Reduce Coronavirus-Related Mortality in Old Mice

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. 247-248
Author(s):  
Christina Camell
Keyword(s):  
Viral Infection ◽  
Cellular Senescence ◽  
Chronically Ill ◽  
The Elderly ◽  
Viral Antibodies ◽  
Age Related ◽  
Old Mice ◽  
Multiple Chronic Diseases ◽  
Pathogen Exposure ◽  
Related Mortality

Abstract The elderly and chronically ill are among groups at the highest risk for morbidity and mortality to several infections, including SARs-CoV-2. Cellular senescence contributes to inflammation, multiple chronic diseases, and age-related dysfunction, but effects on responses to viral infection are unclear. Old mice acutely infected with pathogens that included a SARS-CoV-2-related mouse β-coronavirus experienced increased senescence and inflammation with nearly 100% mortality. Targeting SCs using senolytic drugs before or after pathogen exposure significantly reduced mortality, cellular senescence, and inflammatory markers and increased anti-viral antibodies. Thus, reducing the SC burden in diseased or aged individuals should enhance resilience and reduce mortality following viral infection, including SARS-CoV-2.

scholarly journals Comparative Analysis of Age-Related Changes in Lacrimal Glands and Meibomian Glands of a C57BL/6 Male Mouse Model

2020 ◽  
Vol 21 (11) ◽  
pp. 4169 ◽  
Author(s):  
Chang Ho Yoon ◽  
Jin Suk Ryu ◽  
Ho Sik Hwang ◽  
Mee Kum Kim
Keyword(s):  
Oxidative Stress ◽  
Mouse Model ◽  
Dependent Manner ◽  
Ki 67 ◽  
Aged Mice ◽  
Age Related ◽  
Ifn Γ ◽  
One Year ◽  
Corneal Staining ◽  
Old Mice

It is not known how biological changes in the lacrimal (LGs) and meibomian (MGs) glands contribute to dry eye disease (DED) in a time-dependent manner. In this study, we investigated time-sequenced changes in the inflammation, oxidative stress, and senescence of stem cells in both glands of an aging-related DED mouse model. Eight-week (8W)-, one-year (1Y)-, and two-year (2Y)-old C57BL/6 male mice were used. MG areas of the upper and lower eyelids were analyzed by transillumination meibography imaging. The number of CD45+, 8-OHdG+, Ki-67+, and BrdU+ cells was compared in both glands. Increased corneal staining and decreased tear secretion were observed in aged mice. The MG dropout area increased with aging, and the age-adjusted MG area in lower lids was negatively correlated with the National Eye Institute (NEI) score. Increased CD4+ interferon (IFN)-γ+ cells in LGs were found in both aged mice. An increase in 8-OHdG+ cells in both glands was evident in 2Y-old mice. Reduced Ki-67+ cells, but no change in CD45+ cells, was observed in the MGs of 1Y-old mice. Increased BrdU+ cells were observed in the LGs of aged mice. This suggests that age-dependent DED in C57BL/6 mice is related to inflammation of the LGs, the development of MG atrophy, and oxidative stress in both glands.

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

2009 ◽  
Vol 58 (12) ◽  
pp. 1559-1567 ◽  
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.

scholarly journals Cellular senescence in the aging retina and developments of senotherapies for age-related macular degeneration

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Keng Siang Lee ◽  
Shuxiao Lin ◽  
David A. Copland ◽  
Andrew D. Dick ◽  
Jian Liu
Keyword(s):  
Retinal Pigment Epithelium ◽  
Macular Degeneration ◽  
Cellular Senescence ◽  
Vision Loss ◽  
Inflammatory Responses ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
The Elderly ◽  
Age Related Macular Degeneration ◽  
Age Related

AbstractAge-related macular degeneration (AMD), a degenerative disease in the central macula area of the neuroretina and the supporting retinal pigment epithelium, is the most common cause of vision loss in the elderly. Although advances have been made, treatment to prevent the progressive degeneration is lacking. Besides the association of innate immune pathway genes with AMD susceptibility, environmental stress- and cellular senescence-induced alterations in pathways such as metabolic functions and inflammatory responses are also implicated in the pathophysiology of AMD. Cellular senescence is an adaptive cell process in response to noxious stimuli in both mitotic and postmitotic cells, activated by tumor suppressor proteins and prosecuted via an inflammatory secretome. In addition to physiological roles in embryogenesis and tissue regeneration, cellular senescence is augmented with age and contributes to a variety of age-related chronic conditions. Accumulation of senescent cells accompanied by an impairment in the immune-mediated elimination mechanisms results in increased frequency of senescent cells, termed “chronic” senescence. Age-associated senescent cells exhibit abnormal metabolism, increased generation of reactive oxygen species, and a heightened senescence-associated secretory phenotype that nurture a proinflammatory milieu detrimental to neighboring cells. Senescent changes in various retinal and choroidal tissue cells including the retinal pigment epithelium, microglia, neurons, and endothelial cells, contemporaneous with systemic immune aging in both innate and adaptive cells, have emerged as important contributors to the onset and development of AMD. The repertoire of senotherapeutic strategies such as senolytics, senomorphics, cell cycle regulation, and restoring cell homeostasis targeted both at tissue and systemic levels is expanding with the potential to treat a spectrum of age-related diseases, including AMD.

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