Recipient Organization
MICHIGAN STATE UNIV
(N/A)
EAST LANSING,MI 48824
Performing Department
Food Science
Non Technical Summary
Autoimmune diseases (AD) are chronic and often life-threatening illnesses in which the body attacks itself. ADs affect over 25 million Americans, inflicting tremendous individual suffering and societal burdens. It is estimated that between 80-100 different autoimmune diseases and at least 40 other diseases that have an autoimmune basis. Significantly, autoimmune disease is one of the top 10 leading causes of death in female children and women of all age groups up to 64 years of age. Not surprisingly, women account for 75 percent of AD cases. NIH estimates that annual direct health care costs for autoimmune diseases are nearly 100 billion USD. Well-known examples of autoimmune diseases include systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), psoriasis, scleroderma, multiple sclerosis, Crohn's disease, and ulcerative colitis. While heredity is the primary predisposing factor for AD, both environmental toxicants and diet can influence onset and progression of autoimmunity. Silica is the most abundant minneral on earth, and is also an environmental toxicant etiologically linked to human SLE and other AD (RA, Sjögren's syndrome, scleroderma, systemic vasculitis). An estimated 1.7 million Americans are exposed to respirable silica from farming, manufacturing, mining, hydraulic fracturing, custodial service, construction and military deployment. Consistent with epidemiological studies, airway exposure of silica to SLE-prone mice markedly decreases onset time and increases disease severity. As for diet, animal and clinical studies suggest consuming ω-3 polyunsaturated fatty acids (PUFAs) found in fish oil, most notably docosahexaenoic acid (DHA), can resolve inflammation and may benefit individuals who suffer from AD, including SLE. Our preclinical studies have now taken a step beyond AD symptom reduction to AD prevention by showing that inhibition of toxicant-triggered autoimmunity with dietary DHA might be achievable. ω-3s are the most widely consumed nutritional supplement after multivitamins, taken by ~30 million Americans. DHA consumption by adults up to 5 g per day is considered safe. Given public acceptance and safety of DHA, discovering how supplementation with this and other ω-3s can protect against toxicant-triggered AD could have enormous benefits for American health. This proposal will focus on understanding how dietary ω-3 supplementation influences onset and progression of silica-triggered autoimmunity in a preclinical model of SLE in three objectives:Objective 1. Determine cellular mechanisms by which ω-3s affect silica-triggered SLE.Objective 2. Ascertain how ω-6s and saturated fats in typical Western diet affect the efficacy of ω-3 supplementation as an intervention against onset and progression of silica-triggered SLE.Objective 3. Discern how dietary ω-3 supplementation influences dose-dependent effects of glucocorticoids on onset and progression of silica-triggered SLE.Understanding how dietary lipids influence AD triggering and progression will benefit individuals who have AD or are at-risk for AD in Michigan, the U.S. and the world. As to the long-term impact, data from this study will assist farmers, food processors, and health professionals by providing a foundation for the optimal design of novel foods and supplements for precision medicine treatment/prophylaxis against ADs with ω-s alone or in conjunction with existing therapies.
Animal Health Component
25%
Research Effort Categories
Basic
75%
Applied
25%
Developmental
(N/A)
Goals / Objectives
The long-term goal of this project proposal is to develop robust dietary interventions against devastating autoimmune diseases (ADs) by specifically restructuring the body's cellular membrane lipids. This project is pertinent to two USDA Knowledge Areas: 1) KA502 "New and Improved Food Products" and 2) KA702 "Nutrient Requirements and Function". This work is highly relevant to the overall Michigan AgBioResearch Mission "...to generate advancements in food, health, and the environment" and more specifically, the priority research area of "Nutrition and Health".ADs are chronic and often life-threatening illnesses in which the body attacks itself. ADs affect over 25 million Americans, inflicting tremendous individual suffering and societal burdens. It is estimated that between 80-100 different autoimmune diseases and at least 40 other diseases that have an autoimmune basis. Significantly, autoimmune disease is one of the top 10 leading causes of death in female children and women of all age groups up to 64 years of age. Not surprisingly, women account for 75 percent of AD cases. NIH estimates that annual direct health care costs for autoimmune diseases are nearly 100 billion USD. Well-known examples of autoimmune diseases include systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), psoriasis, scleroderma, multiple sclerosis, Crohn's disease, and ulcerative colitis.Our focus, SLE, is a prototypical multisystem AD primarily affecting women of childbearing age and of color. The Lupus Foundation of America, one of our early funders, estimates that 1.5 million Americans, and at least five million people worldwide, have a form of lupus. SLE results from incompletely understood interactions between an individual's susceptibility genes and environmental triggers that break down immunological tolerance. Early-stage SLE involves chronic autoimmune responses characterized by antibody production against self-antigens and immune complex formation. The latter promote complement activation, mononuclear effector cell infiltration, cytokine/chemokine release, inflammation, and cell death affecting many organs. In the kidney, these responses can manifest as severe glomerulonephritis that can progress to end-stage renal failure and death.While genetically inherited susceptibility (genome) is universally recognized as the primary predisposing factor for AD, environmental factors (exposome) can either potentiate or attenuate AD manifestation. NIH expert committees have identified two environmental factor components critical to AD onset and progression: 1) toxic stressors - see NIEHS Expert Panel Consensus Statement(1); and 2) dietary factors - see NIAID Committee Statement(2). One well-known toxic stressor, crystalline silica (quartz), is the most abundant mineral on earth, and is also an environmental toxicant etiologically linked to human SLE and other AD (RA, Sjögren's syndrome, scleroderma, systemic vasculitis) (3, 4). An estimated 1.7 million Americans are exposed to respirable silica from farming, manufacturing, mining, hydraulic fracturing, custodial service, construction and military deployment (5, 6). Consistent with epidemiological studies, airway exposure of silica to SLE-prone mice markedly decreases onset time and increases disease severity (7-11).As for dietary factors, animal and clinical studies suggest consuming ω-3 polyunsaturated fatty acids (PUFAs) found in fish oil, most notably docosahexaenoic acid (DHA), can resolve inflammation and may benefit individuals who suffer from AD (reviewed in(12, 13)), including SLE. Our preclinical studies have now taken a step beyond AD symptom reduction to AD prevention by showing that inhibition of toxicant-triggered autoimmunity with dietary DHA might be achievable. ω-3s are the most widely consumed nutritional supplement after multivitamins, taken by ~30 million Americans(14, 15). DHA consumption by adults up to 5 g per day is considered safe (16). Given public acceptance and safety of DHA, discovering how supplementation with this and other ω-3s can protect against toxicant-triggered AD could have enormous benefits for American health. This proposal will focus on understanding how dietary ω-3 supplementation influences onset and progression of silica-triggered autoimmunity in a preclinical model of SLE. As described in depth later, there are three objectives:Objective 1. Determine cellular mechanisms by which ω-3s affect silica-triggered SLE.Objective 2. Ascertain how ω-6s and saturated fats in typical Western diet affect the efficacy of ω-3 supplementation as an intervention against onset and progression of silica-triggered SLE.Objective 3. Discern how dietary ω-3 supplementation influences dose-dependent effects of glucocorticoids on onset and progression of silica-triggered SLE.
Project Methods
OBJECTIVE 1. DETERMINE CELLULAR MECHANISMS BY WHICH ω-3s AFFECT SILICA-TRIGGERED SLESub-objective 1.1. Define how DHA and its bioactive metabolites influence silica-triggered inflammasome activation in AMs in vitro and ex vivo. NLRP3 inflammasome activation is central to silica-induced inflammation and toxicity and is consistently observed in MΦs both in vitro and in vivo (75-78). Importantly, DHA and/or its SPMs suppress NLRP3 inflammasome activation in MΦs by the canonical inducers ATP and nigericin (79, 80). A primary mechanism of action for DHA's anti-inflammatory effects is activation of the peroxisome proliferator-activated receptor gamma (PPARγ) and the G-protein receptor (GPR) 120/40, whereas secondary effects of DHA metabolites such as RvD1, RvD2, PD1 and maresin-1 act via the lipoxin A4 receptor (ALX4) and GPR32(79, 81-90). Accordingly, both in vitro and ex vivo models will be used here to test the hypothesis that DHA and DHA-derived SPMs inhibit silica-induced inflammasome activation in AMs and this occurs through selective activation of FA/SPM receptors.Sub-objective 1.2. Understand how DHA and its bioactive metabolites influence silica-induced AM death and af-fect the capacity of AMs to efferocytose cell corpses in vitro and ex vivo. silica exposure evokes cell death in AMs in vitro and in vivo by two principal mechanisms- pyroptosis and apoptosis. Pyroptosis, a lytic-programmed cell death mode, occurs in MΦs following inflammasome-mediated activation of caspase-1(91, 92). In contrast, apoptosis following silica exposure results from LMP-driven release of cathepsins and other proteases(93). During pyroptosis and apoptosis, phosphatidylserine (PS), normally present in the inner leaflet, is revealed on the cell surface (94, 95). PS facilitates recognition by MΦ and consequent engulfment of the cell corpse. Inadequate efferocytosis (an expected result of massive silica-triggered MΦ death) has been linked to lupus(96-98) and other ADs(27, 99-103). Efferocytosis is the process by which dying cells/cell corpses are removed by phagocytes- the net effect being reduced secondary necrosis with attendant alarmin and self-Ag release that drive inflammation and autoimmunity. Central to this Sub-objective, both ω-3s and SPMs have been widely reported to both increase the efferocytotic capacity of MΦs as well as enhance their ability to be recognized as dying cells and be efferocytosed(104-109). Accordingly, here we will employ in vitro and ex vivo models to test the hypothesis that DHA and DHA-derived SPMs suppress silica-induced AM cell death and/or enhance efferocytosis of cell corpses through selective activation of FA and/or SPM receptors.Sub-objective 1.3. Demonstrate in vivo that early suppression of silica-induced inflammasome activation, cell death, self-Ag accumulation and autoantibody production in lung precede DHA's long-term protective effects against silica-triggered systemic autoimmunity. In preliminary studies, dietary DHA suppressed silica-induced pulmonary inflammation, ELT neogenesis, and autoantibody production in the NZBWF1 mouse- this closely corresponded to reduced systemic autoimmune responses and glomerulonephritis. Our current perspective so far, however, is limited to analyses conducted after glomerulonephritis onset- 3 months following silica exposure. Not knowing early in vivo events that precede autoimmunity onset precludes melding AM mechanisms identified above with what happens in the NZBWF1 mouse. Particularly critical will be bridging AM death and self-Ag release (eg, nucleosomes) to autoimmunity (eg. anti-nucleosome and anti-dsDNA antibody production). Furthermore, if DHA supplementation increases survival of silica-laden AMs, it might be further speculated that silica clearance from the lungs is enhanced by AM trafficking via the mucociliary escalator or to draining lymph nodes. Accordingly, we will use female NZBWF1 mice to test the hypothesis that prevention of silica-induced inflammation and autoimmunity by DHA consumption in vivo will correspond in the lung to: 1) suppressed inflammasome activation and inflammation, 2) decreased cell death and self-Ag release, 3) anti-inflammatory mononuclear phagocyte phenotype, 4) proresolving lipid metabolite signature, and 5) altered silica clearance.OBJECTIVE 2. ASCERTAIN HOW ω-6s AND SATURATED FATS IN TYPICAL WESTERN DIET AFFECT THE EFFICACY OF ω-3 SUPPLEMENTATION AS AN INTERVENTION AGAINST ONSET AND PROGRESSION OF SILICA-TRIGGERED SLE. Our goal here is to use a modified TWD (MTWD) to interrogate how ω-6s and SFs affect DHA's anti-lupus effects in our model. Our guiding hypothesis is that the effectiveness of ω-3 supplementation in ameliorating and/or preventing lupus triggering is negatively influenced by the high ω-6 and SF content in the American diet.Sub-objective 2.1. Determine how ω-6s and SFs in typical Western diet influence utility of DHA supplementation as a treatment for suppressing progression and/or promoting resolution of existing silica-triggered lupus in NZBWF1 mice. Our working hypothesis is that consumption of ω-6s and/or SFs interferes with ω-3-mediated amelioration of preexistent autoimmunity initiated by intranasal silica instillation in lupus-prone mice.Sub-objective 2.2. Establish how ω-6s and SFs in a representative Western diet affect the efficacy of DHA supplementation as a preventative for delaying onset and reducing severity of silica-triggered lupus in NZBWF1 mice. Our working hypothesis is that prior and continued consumption of ω-6s and/or SFs will impair the capacity of ω-3s to prevent/postpone initiation and decrease severity of silica-triggered autoimmunity in lupus-prone mice.OBJECTIVE 3. DISCERN HOW DIETARY ω-3 SUPPLEMENTATION INFLUENCES DOSE-DEPENDENT EFFECTS OF GLUCOCORTICOIDS ON ONSET AND PROGRESSION OF SILICA-TRIGGERED SLE. . We will test the hypothesis that dietary ω-3 supplementation will reduce the amount of GC needed to suppress lupus flaring and progression.Sub-objective 3.1. Determine how DHA influences dose-dependent effects of prednisone on initiating autoimmunity and nephritis in NZBWF1 mice after silica-triggering.Sub-objective 3.2. Find out how DHA affects prednisone's effects on long-term autoimmune pathogenesis, kidney injury, and survival in NZBWF1 mice following silica-triggering.