Browsing by Subject "Inflammation"

Now showing 1 - 15 of 15
  • Thumbnail Image
    Item
    Aspirin intervention, inflammation and the oral microbiome
    (2020-10) Onyeaghala, Guillaume
    Specific pro-inflammatory oral taxa have been shown to be increased in the gut microbiome of individuals with colorectal cancer (CRC). Aspirin is associated with decreased risk of colorectal cancer, potentially by modulating the gut and the oral microbiome. However, it remains unclear how pro-inflammatory oral taxa would respond to anti-inflammatory agents such as aspirin. In this dissertation, we aimed to evaluate the effect of aspirin intervention on specific pro-inflammatory oral taxa and inferred functional traits linked to inflammation in a 6-week double-blind placebo-controlled trial.In the first manuscript, we evaluated the effect of aspirin intervention on the relative abundance of pro-inflammatory oral taxa. We found that the change over-time in the relative abundance of 9 out of the 12 pre-specified taxa at the genus level, and 1 out of 2 pre-specified taxa at the family level differed between the aspirin and placebo groups. These preliminary findings suggest that aspirin may change the relative abundance of oral taxa associated with inflammation. In manuscript 2, we evaluated the effect of aspirin intervention on the relative abundance of inferred functional traits linked to the pro-inflammatory bacterial metabolite, lipopolysaccharide (LPS). We did not find an association between aspirin intervention and the change in relative abundance of inferred functional traits for LPS. However, we observed a positive correlation between the relative abundance of pro-inflammatory oral taxa and the relative abundance of inferred functional traits for LPS. These findings are in line with the current literature on bacterial virulence factors. Lastly, we investigated whether inflammation-related oral taxa and inflammation-related gut taxa are correlated and whether oral and gut microbiome communities respond similarly to aspirin. Our results show that aspirin may induce changes in oral and gut alpha diversity in a similar fashion. In addition, our findings of an inverse correlation between SCFA-producing gut taxa and pro-inflammatory oral taxa suggest that studying oral taxa may be important to understanding the link between inflammation and the gut microbiome. Overall, these findings are in line with a growing body of evidence highlighting the role of the oral microbiome in chronic inflammatory disorders of the intestine, including CRC.
  • Thumbnail Image
    Item
    Bioavailability and Biological Efficacy of Phenolic Compounds in Oat and Extra Virgin Olive Oil: Implication of Exercise
    (2018-07) Zhang, Tianou
    Eccentric exercise and atherosclerosis are known to generate reactive oxygen and nitrogen species (RONS) and inflict inflammatory responses, leading to muscle inflammation and coronary artery disease respectively. Selective phenolic compounds from oats (Avenanthramides, AVA) and olive oil (Oleocanthal/Oleacein, Oleo/Olea) have been shown to remove these chemicals and inhibit the progress of inflammation. This dissertation proposed three studies to investigate: (1) The metabolic fate of AVA by measuring plasma concentrations and pharmacokinetic properties of AVA in human after an acute oral ingestion of oat cookies. (2) Whether 8 weeks of dietary supplementation of AVA can affect circulatory immune cells and reduce blood inflammatory markers in response to downhill running (DR) induced muscle inflammation in both male and female subjects. (3) Whether 12 weeks of Oleo/Olea supplementation can inhibit inflammation and endothelial dysfunction in atherosclerotic rats, and combined exercise training would further reduce inflammation and improve immune functions. The findings and conclusions are: (1) AVA found naturally in oats are absorbed in the plasma after oral administration in humans. AVA reach peak plasma concertation 2-3 hours after oral ingestion in human. AVA-B has the slowest elimination rate (Kel) and longest half-life (T1/2) compared to AVA-A and AVA-C, while AVA-C demonstrated the lowest plasma concentrations (Cmax). (2) Oat AVA supplementation reduced circulatory inflammatory cytokine (IL-6) expression and ROS generation (NRB) after DR. AVA in oats also inhibited expression of chemokines (MIP-1β, MCP-1), cell adhesion molecule (VCAM-1) and colony stimulating factors (GM-CSF, G-CSF) induced by DR. Although circulatory immune cells were not affected by oat AVA supplementation, oat supplementation decreased circulatory monocytes activation (CD14+) while oat AVA inhibited neutrophils (CD11b+) and increased NK cells (CD56+) activation after DR. (3) High Oleo/Olea diet tends to increase circulatory leukocytes, granulocytes, neutrophils percentage and inflammatory cytokines (MCP-1, RANTES, NAP-3, M-CSF, GM-CSF) but decrease lymphocytes percentage and anti-inflammatory cytokines (IL-10) in sedentary rats, whereas exercise training significantly reversed these trends of immune markers induced by EVOO supplementation.
  • Thumbnail Image
    Item
    Changes in endocannabinoid signaling contribute to the anti-hyperalgesic effect of URB597 in a murine model of persistent inflammation.
    (2011-09) Lindberg, Amy Elizabeth
    Modulation of endocannabinoid neurotransmission has a therapeutic benefit in the treatment of inflammatory pain. Studies in this thesis investigated endocannabinoid signaling in a murine model of persistent, peripheral inflammation. Specifically, the ability of URB597, an inhibitor of fatty acid amide hydroxylase (FAAH), which degrades the endogenous cannabinoid anandamide, to reduce mechanical hyperalgesia associated with inflammation was determined. The first study tested whether local injection of URB597 dose-dependently reduced mechanical hyperalgesia associated with persistent inflammation. Inflammation was induced by injection of Complete Freund's Adjuvant (CFA) in the hind paw of mice and mechanical hyperalgesia was determined using a series of von Frey filaments. The first part of the study resolved that local injection of URB597 dose-dependently reduced mechanical hyperalgesia associated with persistent inflammation and decreased mechanical sensitivity in naïve mice. However, injection of URB597 did not result in increased endocannabinoid content in the plantar skin ipsilateral to the injection as would be expected based on the known mechanism of action of URB597. The second and third studies investigated the effect of inflammation on levels of FAAH, endocannabinoids and cannabinoid (CB)-1 receptor in naïve and CFA-injected mice to understand the neurochemistry underlying the anti-hyperalgesic effect of URB597. Levels FAAH mRNA decreased and enzyme activity trended toward a decrease in the plantar skin of the inflamed hind paw compared to tissue from naïve mice, but inflammation did not alter level of anandamide in plantar skin ipsilateral to the injections. In contrast, an increase in FAAH mRNA was accompanied by a decrease in the level of anandamide in dorsal root ganglia (DRGs) ipsilateral to the inflamed hind paw compared to naïve mice. In addition, there is an upregulation of functional CB1 receptors in DRGs ipsilateral to the inflamed hind paw in CFA-injected mice compared to DRGs from naïve mice. Together, these data support a model in which reduced synthesis of AEA in the primary afferent neurons may contribute to the mechanical hyperalgesia associated with peripheral inflammation, and upregulation of CB1 receptors on the primary afferent neurons affected by inflammation may be a compensatory response to decreased basal activation of AEA.
  • Thumbnail Image
    Item
    Determining the effect of lipid nanoemulsions on insulin signaling and the inflammatory pathways at the Blood-Brain Barrier
    (2022-01) Nair, Sanjana
    Several studies have shown that metabolic disorders such as type-2 diabetes (T2DM) play a role in propagating neurodegenerative disorders like Alzheimer’s Disease (AD)(1). As the brain is an insulin-sensitive organ and requires insulin for promoting neuronal integrity and function, impairment of insulin signaling in the CNS has huge implications for memory and cognition(2). Hyperinsulinemia observed in AD and T2DM contributes to vascular inflammation, which in turn, leads to endothelial insulin resistance by impairing insulin receptor (IR) and insulin resistance substrate (IRS)-1(1). The insulin resistance leads to a compensatory increase in circulating insulin leading to hyperinsulinemia. In addition to the impairment of insulin signaling, another hallmark of AD is lipid dysfunction(3). The lipid bilayer of the Blood-Brain Barrier (BBB) endothelial cells harbors lipid rafts that play a vital role in transcytosis and maintaining various signaling functions(3). Lipid metabolism at the BBB changes with age and diet and results in a decrease of unsaturated fatty acid content and an increase in lipid peroxidation. In this study, we hypothesize that the delivery of lipid nanoemulsion, which is rich in unsaturated fatty acids, will improve insulin signaling at the BBB, and ameliorate insulin resistance caused by cytokines like TNF-α. This, in turn, is expected to decrease VCAM-1 expression and mitigate BBB dysfunction. This hypothesis has been verified by treating BBB endothelial cells with inflammatory cytokines like TNF-α, which inhibited insulin signaling and increase the expression of vascular cell adhesion molecule-1 (VCAM-1), a marker for endothelial inflammation. Alternatively, exposure to soybean oil nanoemulsion (SNEs) like that of Humulin® triggered insulin signaling and reduced VCAM-1 expression. The results showed that the SNEs have the ability to overcome the resistance induced by TNF-α, and increased the insulin signaling to the level comparable to Humulin® control and the opposite effect was seen when the cells were treated with nanoemulsion rich in saturated fatty acids. Lipid-based nanoemulsion could be used as a strategy to mitigate insulin resistance and the consequent inflammation commonly seen in neurodegenerative disorders like AD.
  • Thumbnail Image
    Item
    The effects of two modes of exercise training on plasma biomarkers of inflammation and oxidative stress in patients with symptomatic peripheral artery disease
    (2014-08) Salisbury, Dereck Lee
    Introduction: Peripheral Artery Disease (PAD) is a manifestation of progressive atherosclerosis involving the main conduit arteries supplying the lower extremities. It is well known that atherosclerotic cardiovascular disease including PAD, is related partly to vascular inflammation and oxidative stress. Treadmill walking exercise to moderate claudication pain is considered the gold standard for improving walking distance in patients with PAD and claudication. Our group had previously reported that non-ischemia inducing upper body ergometry exercise training improves pain-free and maximal walking distance similar to ischemic inducing treadmill exercise training in patients with claudication. The influence of ischemic and non-ischemic inducing exercise training on systemic inflammation and vascular oxidative stress remains to be fully elucidated. Methods: A total of 75 patients (59 male and 16 female) with symptomatic PAD from the randomized controlled trial, Exercise Training to Reduce Claudication (EXERT), were used in a secondary analysis of inflammation and oxidative stress. Analysis of plasma for TNF alpha, IL-10, and F2 Isoprostane were performed at baseline and following 12 weeks of moderate intensity, claudication inducing treadmill training (T), upper body ergometry training (UBE), or usual care (C). Analysis of covariance was used to evaluate changes among groups for all biomarkers following intervention, using baseline level as a covariate. Pearson's correlation coefficient was used to assess correlation among baseline plasma biomarkers and physical and physiological variables. Results: After 12 weeks of intervention, all patients, regardless of the group increased TNF alpha levels. In particular, patients randomized to the UBE group significantly increased TNF alpha levels compared to the control group after adjusting for baseline TNF alpha and allopurinol (a significant covariate). Participants in the treadmill group had non-significant increases in IL-10, while all groups showed non-significant decreases in F2 Isoprostanes. Additionally there was no significant correlation between baseline plasma inflammatory and oxidative stress biomarkers, with physical and physiological variables such as ankle-brachial index, pain-free walking distance, and maximal walking distance at baseline. However, body mass index was significantly correlated to baseline TNF alpha levels (r=0.228, p=0.05). Conclusion: Moderate intensity UBE training appears to significantly increase the proinflammatory cytokine TNF alpha compared to a control group in patients with symptomatic PAD. However, all groups increased TNF alpha after 12 weeks of intervention, which contradicts the deemed anti-inflammatory effect of aerobic exercise training. It is clear that further study is required to establish if exercise training in patients with claudication is anti-inflammatory.
  • Thumbnail Image
    Item
    Examining and improving the chemopreventive efficacy of curcumin
    (2012-09) Grill, Alexander E.
    Curcumin, a polyphenol extracted from turmeric, has shown chemopreventive and chemotherapeutic effects against cancer. However, curcumin suffers from poor bioavailability, which limits its clinical use. We hypothesized that using novel microparticle and SMEDDS formulations will improve the pharmacokinetics and therapeutic efficacy of curcumin. Initial studies examined the anticancer efficacy of curcumin loaded poly(lactide-co-glycolic acid) (PLGA) microparticles in a transgenic mouse model of human epidermal growth factor receptor-2 (HER-2) cancer, Balb-neuT. HER-2 is overexpressed in 30% of breast cancer cases and is associated with poor prognosis and high incidence of metastasis. Curcumin microparticles delayed tumor appearance by 2-3 weeks and were associated with a decrease in VEGF protein levels and CD-31+ microvasculature compared to empty microparticles. However, when compared to saline controls, blank microparticles appeared to accelerate tumorigenesis. Blank PLGA microparticles were shown to activate NF-kB signaling, indicating systemic inflammation after injection. The delay in tumorigenesis with curcumin-loaded microparticles was likely attributed to the anti-inflammatory effects of curcumin. Future studies will examine the systemic effects of blank PLGA microparticles as well as explore other polymers for curcumin microparticle delivery. A self microemulsifying drug delivery system (SMEDDS) was examined for oral delivery of curcumin. The SMEDDS formulation solubilized curcumin at high concentrations (~45 mg/mL). However, administering curcumin in the SMEDDS formulation did not increase curcumin bioavailability but increased gut absorption, evident by increased plasma curcumin glucuronide levels. We hypothesized that oral bioavailability of curcumin could be enhanced by increasing its absorption and decreasing metabolic clearance simultaneously. Microsomal studies showed that silibinin and quercetin inhibited curcumin glucuronidation in vitro. Piperine, which was shown to improve curcumin bioavailability previously, silibinin and quercetin were administered with curcumin in vivo. Coadministration of curcumin and piperine showed high variability after dosing. Addition of silibinin significantly improved curcumin bioavailability (3.5 fold) compared to curcumin alone. Future studies should examine the chemopreventive potential of curcumin and silibinin for HER-2+ breast cancer.
  • Thumbnail Image
    Item
    The fatty acids - inflammation relationship across the lifecycle
    (2011-10) Wang, Huifen
    Dietary fatty acid intake, reflected by the endogenous fatty acid profile, has been associated with the pathogenesis and progression of cardiovascular diseases (CVD). Additional evidence is needed about the specific roles of individual fatty acids in the pathogenesis of inflammation, which is closely linked to CVD risk factors and interwined with oxidative stress and hemostatic dysfunction. It is also important to explore such relationships across the lifecycle. This dissertation, which includes four manuscripts, investigates the relations between fatty acids, biomarkers of inflammation (and oxidative stress and hemostasis), and cardiovascular health among different age groups. Specifically, the influences of adiposity and a genetic variant on the fatty acid/inflammation relations were also explored. The first manuscript used data from a study of obesity, insulin resistance and CVD risk factors in adolescents. A cross-sectional analysis was conducted to examine whether overweight status modified the relations between serum phospholipid fatty acids from dairy fats (i.e. 15:0 and 17:0 fatty acids) and inflammation/oxidative stress among adolescents with a mean age of 15 years. Inverse associations were found between dairy fatty acids and three biomarkers of inflammation and oxidative stress among overweight adolescents, but not their normal weight counterparts. In additional analyses, we further examined the same study question on other fatty acids and observed similar effect modification of adiposity. Only in overweight adolescents, but not in normal adolescents, 18:0 and 20:3ù6 fatty acids were positively, while 20:4ù6 and 22:6ù3 fatty acids were inversely, related to inflammation/oxidative stress. The second manuscript examined whether the cross-sectional relations between dietary intakes of polyunsaturated fatty acids (PUFA) and inflammation differed by genetic variant, peroxisome proliferator-activated receptor gamma (PPARã) Pro12Ala polymorphism. A biracial cohort of middle-aged adults enrolled in the year-20 exam of the Coronary Artery Risk Development in Young Adults (CARDIA) study was studied. In women, higher dietary intakes of 20:4ù6, 20:5ù3 and 22:6ù3 fatty acids were related to lower levels of IL-6 (an inflammatory biomarker) among Ala allele carriers. In contrast, these PUFA/IL-6 relations were positive among male Ala carriers, and absent among female Pro homozygotes. Male Pro homozygotes who consumed more 20:5ù3 and 22:6ù3 fatty acids tended to have a lower IL-6 level. The last two manuscripts were both prospective studies using data from the Atherosclerosis Risk in Communities (ARIC) study, which enrolled middle-aged adults. This cohort has been followed since year 1987-89. Manuscript 3 examined the interactions between dietary fatty acid intake and inflammatory/hemostatic factors in relation to incident coronary heart disease (CHD) and ischemic stroke (IS). Dietary intakes of 18:2ù6 and 20:4ù6 fatty acids were found to modify the associations between serum albumin and incident CHD/IS. The prediction of low serum albumin level, a potential inflammatory biomarker, on incident CHD/IS was attenuated with increasing intake of 18:2ù6 fatty acid or decreasing intake of 20:4ù6 fatty acid. Manuscript 4 included 3,715 ARIC participants enrolled at the Minnesota field center who had plasma phospholipid fatty acid measurements. In manuscript 4, the focuse was to determine whether inflammation/hemostasis mediated the relation of phospholipid fatty acids with incident CHD and IS. Inflammation and hemostasis, represented by levels of factor VIIIc (VIIIc), white blood cell count (WBC) and fibrinogen, mediated the positive associations of 18:0 and 20:3ù6 fatty acids with incident CHD. A similar but less significant pattern was found for 16:1ù7 in relation to incident IS. Lower WBC, but not VIIIc or fibrinogen, partially explained the inverse relations of 17:0 and 20:4ù6 fatty acids with incident CHD. In conclusion, this dissertation documents the associations between diverse fatty acids, inflammation and the development of CVD among different age-groups. The findings have enhanced the understanding of the health effects of individual fatty acids and the underlying mechanisms of fatty acid-inflammation-CVD relations, which are useful for advising food manufacturers and guiding CVD prevention.
  • Thumbnail Image
    Item
    Functional role of receptor-interacting protein 140 (RIP140) in adipocyte dysfunctions and inflammatory response in macrophages.
    (2012-03) Ho, Ping-Chih
    The prevalence of metabolic diseases in modern society, including Type II diabetes mellitus (T2DM), hypertension and cardiovascular diseases, is a major burden on health care systems. Among these diseases, T2DM and its associated complications contribute to the progression of other metabolic diseases such as fatty liver diseases and atherosclerosis. Understanding the initiation and progression of T2DM is critical for developing treatments for T2DM and its associated metabolic disorders. Adipocyte dysfunctions and chronic inflammation have been shown recently to play essential roles in the progression of T2DM. Normally, adipocytes can store energy as triglycerides, fine-tune other metabolic tissues¡¦ lipid and glucose metabolism, and secreted cytokines (adipokines) to modulate immune response. In T2DM or obesity, adipocytes become dysfunctional, with increased lipolysis, an altered adipokine profile, and decreased insulin sensitivity and glucose uptake ability. These changes affect not only the adipocytes themself but also systemic glucose and lipid metabolism. In obese patients and in the high-fat diet (HFD)-fed mouse model, increased inflammatory response in macrophages also contributes to adipocyte dysfunction. The escalated inflammatory response plays pathophysiological roles in various metabolic disorders, including atherosclerosis and arthritis, and increases the incidence of septic shock. However, the underlying mechanisms for initiation of adipocyte dysfunctions and escalation of inflammatory response remain unclear. Receptor-interacting protein 140 (RIP140) is a co-regulator for various transcription factors and nuclear receptors and is expressed mainly in macrophages and metabolic tissues, including adipocytes, hepatocytes and muscle cells. RIP140 affects the progression of T2DM through its nuclear activity as shown by the resistance of knockout mice to diet-induced diabetes and its associated metabolic disorders. In my studies, I found that when I used HFD feeding to induce T2DM, RIP140 could accumulate within the cytoplasm of adipocytes. I further demonstrated that cytoplasmic RIP140 not only interacted with AS160 to impede GLUT4 vesicle trafficking and adiponectin vesicle secretion, but also formed a complex with perilipin A to enhance lipolysis. These findings suggest that HFD feeding can alter RIP140¡¦s cellular distribution, which leads to adipocyte dysfunctions including higher lipolysis, lower glucose uptake, and reduction in adiponectin secretion. I also showed that HFD feeding promoted cytoplasmic accumulation of RIP140 in adipocytes through a PKCϵ-dependent signaling pathway by enhancing intracellular lipid content (as an intrinsic stimulus) and circulating endothelin-1 (as an extrinsic stimulus). Most importantly, administration of a selective ET-1 receptor anatagonist, ambrisentan, reduced HFD-induced cytoplasmic accumulation of RIP140 in adipocytes and further ameliorate hepatic steatosis and insulin sensitivity in vivo. These findings reveal the novel roles of cytoplasmic RIP140 in adipocyte dysfunctions and provide evidence for cytoplasmic RIP140 as a promising target for treatment of T2DM. Recently, RIP140 has also been shown to affect proinflammatory cytokine production by functioning as co-activator for NF-fÛB in macrophages. I showed that HFD feeding up-regulated RIP140 expression by promoting intracellular cholesterol level which led to increased proinflammatory potential in macrophages. In this study, intracellular cholesterol level regulates RIP140 expression by decreasing microRNA-33a, which targeted RIP140 via a conserved region in 3¡¦-UTR of RIP140 mRNA. I further discovered that TLR ligands could trigger RIP140 degradation to resolve inflammation. This RIP140 degradation was modulated by RelA-recruited SCF E3 ligase and Syk-mediated phosphorylation on RIP140. My studies in macrophages demonstrate that RIP140 in macrophages can be modulated by a HFD to affect the systemic inflammatory response and further suggest that defects in RIP140 degradation may cause non-resolving inflammation which is involved in septic shock and various metabolic disorders. Taken together, my studies provide evidence for the novel functions of RIP140 in adipocyte dysfunction and inflammatory response in macrophages and determine the mechanisms by which HFD affect RIP140¡¦s distribution and expression in adipcoytes and macrophages. These findings contribute to our understanding of how HFD causes adipocyte dysfunctions and increase inflammatory response.
  • Thumbnail Image
    Item
    PATHWAYS TO DEPRESSIVE SYMPTOMS AND INFLAMMATION FROM EARLY PSYCHOSOCIAL AND NUTRITIONAL ADVERSITY: A LONGITUDINAL STUDY OF CHILEAN YOUTH
    (2020-06) Reid, Brie
    Exposure to early life adversity (ELA) is thought to increase the risk of later psychopathology through alterations in immune system functioning, notably through increased inflammation. However, nutritional adversities such as iron deficiency may arise from and co-occur with ELA. Psychosocial adversity and nutritional adversities together may play a causal role in the development of psychosocial maladjustment via increases in circulating inflammatory factors. The present study investigates whether psychosocial ELA predicts iron status early in life and uses structural equation modeling to determine if ELA and iron status in infancy predict increased inflammation in adolescence and depressive symptoms in emerging adulthood. The study is a follow-up of infants from working-class communities in Santiago, Chile, who participated in a preventive trial of iron supplementation at six months of age. Anthropometrics, stressful life events, maternal depression, socioeconomic status, support for child development, and iron status were measured in the first year of life, five years, ten years, and adolescence. In adolescence, participants provided blood samples for inflammation assessments (CRP, WBC, neutrophil to lymphocyte ratio, and monocyte count). In emerging adulthood (21y), participants provided self-reported depressive symptoms. ELA in infancy predicted iron status in infancy and depressive symptoms in emerging adulthood. However, ELA did not directly predict increased inflammation in adolescence, and increased inflammation did not predict increased depressive symptoms. Iron status in infancy predicted increased monocyte count in adolescence, and ELA in infancy predicted higher levels of monocytes indirectly through iron status in infancy. These findings provide novel evidence of the association between postnatal ELA and iron status and suggest that ELA predicts depressive symptoms independent of inflammation in this population. These findings also provide evidence of a novel pathway by which early adversity and nutrition program the developing immune system.
  • Thumbnail Image
    Item
    Regulation and Effects of Heme-Oxygenase-1 Expression in Chronic Inflammation.
    (2010-06) Beckman, Joan Denise
    Heme oxygenase-1 (HO-1) enzyme plays critical role in metabolizing the excess heme generated during hemolysis in pathological conditions, such as sickle cell disease. We and others have previously demonstrated that during chronic intravascular hemolysis the expression of HO-1 protein is not sufficient to reduce the oxidative burden of free heme in the vasculature, leading to oxidative stress and vascular inflammation. This proposal examined two areas critical to the understanding of HO-1 expression and function during inflammation: the role of post-transcriptional regulation in control of protein expression and the importance of its by-product carbon monoxide (CO) in mediating anti-inflammatory, anti-apoptotic effects. The research utilized a murine sickle model which has perturbations of heme catabolism leading to oxidative stress and inflammation. Studies in this model will test whether HO-1, or its by-products, can therapeutically alter the natural history of sickle cell disease. In addition, cell culture models in which heme levels are controlled were used to explore microRNA regulation of heme oxygenase-1 (HO-1) expression. Combined these experimental endeavors aim to identify new aspects of HO-1 research.
  • Thumbnail Image
    Item
    The Role of Host Factors in the Control of Gut Microbiota and Inflammation in Diet-Induced Obesity and During Aging
    (2019-11) Qiu, Xiaoxue
    Disruptions of microbiota and inflammatory homeostasis in the gut have been implicated in the metabolic dysregulation of diet-induced obesity (DIO) and aging. However, the involvement of host factors in these disturbances remains unclear. Lipocalin 2 (Lcn2) has previously been identified as an adipocytokine and characterized as an important regulator of diet-induced obesity and inflammation. Lcn2, as an anti-microbial peptide is also expressed in intestine, and the upregulation of intestinal Lcn2 has been previously reported in inflammatory bowel disease to protect against colitis-associated intestinal inflammation and to regulate gut microbiota composition. In chapter 2 and 3, we investigated the role and mechanism of Lcn2 in the regulation of gut microbiota composition and microbial metabolism in diet-induced obesity. We also investigated the role of Lcn2 in the control of age-related reshaping of gut microbiota and brain health via a gut-brain axis during aging. We demonstrate that intestinal Lcn2 expression and secretion into the gut lumen is regulated by high fat diet (HFD) consumption and aging in a time-dependent manner. Lcn2 plays a protective role in HFD-induced and age-associated gut microbiota dysbiosis. Our results suggest that Lcn2 regulates gut microbiota composition and intestinal inflammation through an independent mechanism, and Lcn2 likely regulates the growth of siderophore-producing bacteria directly. Lcn2 deficiency alters the production of microbial metabolites, particularly short-chain fatty acids (SCFAs) during DIO and aging, thereby contributing to the development of obesity and age-related disease. In chapter 2, our findings suggest that the induction of Lcn2 expression and secretion at the early stage of HFD consumption is a host defensive mechanism against HFD-induced disruption of gut commensal and inflammatory homeostasis, whereas long-term HFD challenge disrupts the protective role of Lcn2 by disturbing the secretion of Lcn2 into the gut lumen. Moreover, we have identified 45 bacteria with altered abundances in Lcn2 knockout (LKO) mice during DIO. Through the correlation analysis between body weight and bacteria/metabolites, we highlight that Lcn2 controls the development of obesity through regulating the growth of the microbes (Dubosiella and SCFA-producing bacteria) and the production of microbial metabolites (e.g. SCFAs). In chapter 3, we found that Lcn2 deficiency impairs cognitive function and alters behavioral outcomes in old (18-month-old) mice. Sixteen bacteria at the family level were identified to be differentially abundant in LKO mice. Of those 16 bacteria, health-promoting bacteria (e.g. SCFA-producing bacteria Muribaculaceae) have significantly less prevalent in old LKO mice. Consistently, Old LKO mice display lower levels of fecal butyrate compared to old wild-type (WT) mice. Our data suggest a potential mechanism involving gut microbiota and its associated metabolites for the role of Lcn2 in the control of age-related neurodegenerative diseases. Chronic Low-grade inflammation in multiple tissues and organs is commonly accompanied with aging and its-related diseases, such as obesity, type 2 diabetes, neurodegenerative diseases, and cancers. Macrophages play a critical role in local tissue inflammation, which contributes to metabolic complications. Macrophage polarization is tightly associated with its metabolic reprograming and immune dysfunction. In chapter 4, we explored intracellular molecules/pathways that connect these alterations in inflammatory macrophages. We found that the expression of guanylate binding protein 1 (Gbp1), an intracellular anti-microbial protein is significantly decreased in white adipose tissue of HFD-fed and aged mice. Downregulation of Gbp1 expression results in macrophage polarization towards a pro-inflammatory phenotype. Gbp1 knockdown (Kd) macrophages have impaired mitochondrial function and decreased mitophagy activity. More interestingly, Gbp1 Kd macrophages experience senescence as evidenced by increased activation of AMPK-p53 pathway and positive staining of β-galactosidase. Collectively, these observations highlight important roles of Gbp1 in improving mitochondrial dysfunction, preserving immune function, and attenuating senescence of macrophages during inflammatory stress and aging.
  • Thumbnail Image
    Item
    The Role of Inflammation and Oxidative Stress in Adipocytes in the Development of Insulin Resistance
    (2015-08) Burrill, Joel
    Inflammation plays a critical role in the pathology of obesity-linked insulin resistance and is mechanistically linked to the effects of macrophage-derived cytokines on adipocyte energy metabolism, particularly that of the mitochondrial branched chain amino acid (BCAA) and tricarboxylic acid (TCA) pathways. To address the role of inflammation on energy metabolism in adipocytes we utilized high fat fed C57Bl/6J mice and lean controls and measured down regulation of genes linked to BCAA and TCA cycle metabolism selectively in visceral but not in subcutaneous adipose tissue, brown fat, liver or muscle. Using 3T3-L1 cells, TNFα and other pro-inflammatory cytokine treatments reduced the expression of genes linked to BCAA transport and oxidation. Consistent with this, [14C]-leucine uptake and conversion to triglycerides was markedly attenuated in TNFα-treated adipocytes whereas conversion to protein was relatively unaffected. Since inflammatory cytokines lead to induction of ER stress, we evaluated the effects of tunicamycin or thapsigargin treatment of 3T3-L1 cells and measured a similar down regulation in the BCAA/TCA cycle pathway. Moreover, transgenic mice overexpressing XBP1s in adipocytes similarly down regulated genes of BCAA and TCA metabolism in vivo. These results indicate that inflammation and ER stress attenuate lipogenesis in visceral adipose depots by down regulating the BCAA/TCA metabolism pathway and are consistent with a model whereby the accumulation of serum BCAA in the obese insulin-resistant state is linked to adipose inflammation.
  • Thumbnail Image
    Item
    Studies of fatty acid binding proteins and inflammatory lipids in adipose biology
    (2012-12) Hellberg, Anna Kristina
    There are a number of factors spurred by obesity that contribute to the development of insulin resistance, such as adipose tissue inflammation and elevated circulating fatty acid levels. Fatty Acid Binding Proteins (FABP) are soluble proteins that bind long chain fatty acids and other hydrophobic molecules and facilitate their intracellular transport. Mice with genetic disruption of Adipocyte FABP (AFABP) exhibit an insulin sensitizing and anti-inflammatory phenotype on a high-fat diet compared to wild type littermates, however the molecular mechanisms are not completely understood. The goal of the studies presented herein was to gain further insights into the role of AFABP in the development of obesity-related insulin resistance. We identified a small molecule inhibitor of AFABP, HTS01037, that upon treatment of cultured cells recapitulates the beneficial phenotypes observed in AFABP knock out mice. Structural studies were undertaken to characterize the effect of ligand binding to AFABP utilizing x-ray crystallography. More specifically the structures of AFABP bound to one inflammatory lipid, 4-HNE, and the pan-specific FABP inhibitor, HTS01037 were determined. In addition, we found that inflammatory lipids, particularly leukotriene C4, are elevated in obese adipose tissue and are produced by macrophages in response to fatty acid treatment in a FABP-dependent manner.
  • Thumbnail Image
    Item
    Study of cellular mechanisms of inflammation and the involvement of mast cells in disease
    (2013-07) Manning, Benjamin Michael
    The principal motivation of this dissertation is to expand the utility of single-cell microelectrochemical methods, specifically carbon-fiber microelectrode amperometry (CFMA), beyond the study of fundamental cellular biophysics and toward applications investigating the cellular signaling networks in inflammation. From an analytical perspective, the inflammatory response presents several technical challenges. The inherent complexity of the immune system makes unraveling the pathogenesis of inflammatory disease a particularly challenging endeavor. An ability to detect and monitor immune cell signaling, at low, physiologically relevant concentrations and in the presence of a complex biological matrix is critical. Furthermore, although the use of bulk in vitro assays are essential for any research in biological systems, the capacity to study important cellular signaling processes at the single cell-level carries several added advantages. For these reasons, CFMA has substantial potential as a unique tool for the study of immune cell signaling. Mast cells, in particular, are an ideal model for this research because 1) they're found in most connective tissues and mucosal surfaces throughout the body, 2) they posses a broad capacity to regulate the immune response and are thought to take part in the progression of many inflammatory diseases, and 3) they release electroactive serotonin, along many other preformed immune-active mediators, via exocytosis which can be monitored by CFMA. The first part of this dissertation consists of several examples wherein CFMA is used to study mast cell degranulation in response to an altered in vivo inflammatory microenvironment, such as the chronic inflammation associated with sickle hemoglobin expression (Chapter 2), chronic in vivo morphine exposure (Chapter 2), and the effects of the endogenous opioid receptor system (Chapter 3). These chapters are followed by research that highlights the advantages of CFMA for the direct comparison of different mast cell stimulation conditions, including a study of chemokine-induced mast cell degranulation to explore the critical interactions between mast cells and airway smooth muscle in asthma (Chapter 4) as well as neuropeptide-induced mast cell degranulation to characterize mast cell function in neurogenic inflammation (Chapter 5). Collectively, this work presents CFMA as a promising technique for the study of cellular signaling in inflammatory disease.
  • Thumbnail Image
    Item
    Targeting the PPARγ and ER pathways via modulation of inflammation in the tumor microenvironment: a novel lung cancer prevention strategy
    (2019-05) Louiselle, Erika
    Lung cancer exceeds all other diagnosed cancers in annual mortality, surpassing the top two annually diagnosed cancers breast and prostate, combined. The vast majority of diagnosed lung cancer cases are in current or former smokers, accounting for 85% of all cases. The number of diagnosed lung cancer cases continues to rise, addressing the need for novel intervention strategies. Despite current advances in chemoprevention for other less-fatal types of cancer, the only currently recognized chemopreventive strategy for lung cancer is smoking cessation. However, former smokers retain a 2.5-fold increased risk of developing lung cancer compared with never smokers, despite cessation efforts. About 40% of all newly diagnosed lung cancers occur in former smokers. As such, chemoprevention strategies for lung cancer are direly needed for the large and ever-growing high-risk population. Preclinical evaluation of existing therapies with established safety and efficacy profiles represents a fruitful opportunity to advance the field. Identification of ERβ expression has been found to be a lucrative method to identify lung cancers that confer poor survival and presents as a potential target for chemopreventive efforts. Preclinical evaluation of anti-estrogens in cell lines and mouse models of lung cancer shows great promise in advancing this class of drugs towards future clinical use in lung cancer prevention. Furthermore, anti-estrogens such as fulvestrant, a complete ER antagonist, have shown anti-tumorigenic activity in lung cancer and others such as tamoxifen have already been successfully implemented in both primary and secondary breast cancer prevention modalities. Preclinical and clinical evidence underpinning the importance of managing ER signaling to control lung cancer initiation and progression, although efficacious, alludes to the potential for increased efficacy when used in combination with other agents. Pioglitazone, a synthetic peroxisome proliferator-activated receptor gamma (PPARγ) agonist belonging to the thiazolidinediones (TZDs) drug class has also been used in preclinical studies to mitigate lung tumorigenesis, progression, and metastasis after a retrospective analysis found that diabetics using TZDs experienced a 33% reduction in lung cancer incidence. PPARγ has also been implicated as a protective pathway in lung cancer initiation and progression in early phase clinical testing. Patients with improved histology scores demonstrated a link between an increased ER gene signature and positive-response to PPARγ activation, which conferred a chemopreventive effect in dysplasias with a persistent and progressive phenotype. This link presents a unique opportunity to utilize two known mechanisms that are efficacious in protecting against carcinogen-induced lung cancer initiation and progression. Cross-talk between PPARγ signaling and estrogen receptor (ER) signaling has also been previously reported in other cancer models. NNK is a principal carcinogen in cigarette smoke, and along with its ability to induce mutations in oncogenes, NNK can act as an inflammatory mediator of the tumor microenvironment (TME) by promoting macrophage infiltration into the lungs. Furthermore, in previously reported NNK-models of lung cancer, immune cells thought to be macrophages that were positive for both aromatase and estradiol were localized to preneoplastic lesions. Taken together, macrophages are hypothesized to play a key role in regulation of the lung TME both through ER-dependent and independent mechanisms, and both ER and PPARγ pathways are also known to be functional. To develop a novel approach to prevent lung cancer, preclinical studies were developed to evaluate the therapeutic potential and chemopreventive capabilities of two FDA-approved agents, pioglitazone and fulvestrant, re-purposed in a lung cancer tumor microenvironment (TME) in vitro model and an NNK-induced adenocarcinoma chemoprevention in vivo model. To test pioglitazone and fulvestrant in a preclinical model simulating the lung TME, we selected a human NSCLC adenocarcinoma cell line with a similar KRAS mutational signature found in smoking-induced lung cancer and a human immortalized macrophage cell line. Additionally, we tested the effects of pioglitazone and fulvestrant in a murine primary cell culture model, utilizing mouse-derived adenocarcinoma cells immortalized from NNK-induced in vivo tumors and primary murine bone marrow-derived macrophages (BMDMs).