The proposed studies will address fundamental questions regarding the mechanisms underlying inflammation-induced enhancement of both hyperactive (contractile) and proliferative (synthetic) states of human airway smooth muscle (hASM), which are hallmarks of asthma. Identifying these mechanisms is the key to developing novel therapeutic targets for asthma. Our central hypothesis is that in hASM, inflammatory cytokines induce sarco-endoplasmic reticulum (SR/ER) stress leading to reduced expression of the mitochondrial fusion protein mitofusin 2 (Mfn2), and that this pathway plays a central role in asthma by triggering both hyper reactive (contractile) and proliferative (synthetic) states.
Four Specific Aims are proposed:
Specific Aim 1 : To determine the impact of inflammatory cytokines on SR/ER stress, Mfn2 expression and mitochondrial fragmentation. In this aim, we will use dissociated hASM cells and tissue from normal and asthmatic patients to test the hypothesis that inflammatory cytokines trigger SR/ER stress due at least in part to an increase in ROS generation, and that SR/ER stress leads to reduced Mfn2 expression and increased mitochondrial fragmentation.
Specific Aim 2 : To determine the functional impact of SR/ER stress and reduced Mfn2 expression. In this aim, we will use dissociated hASM cells and tissue from normal and asthmatic patients to test the hypothesis that in hASM, inflammatory cytokine-induced SR/ER stress and reduced Mfn2 expression uncouples mitochondria and the SR/ER, thereby reducing mitochondrial Ca2+ buffering leading to elevated [Ca2+]cyt and force responses to agonist stimulation.
Specific Aim 3 : To determine the impact of SR/ER stress and reduced Mfn2 on hASM cell proliferation. In this aim, we will use dissociated hASM cells and tissue from normal and asthmatic patients to test the hypothesis that inflammatory cytokines increase hASM cell proliferation as a result of decreased Mfn2 expression.
Specific Aim 4 : To determine the efficacy of therapeutic approaches targeting SR/ER stress in alleviating airway hyper reactivity and remodeling in a mouse model of asthma. In this aim, we will use a mixed allergen mouse model to test the hypothesis that targeting SR/ER stress using chemical chaperones (e.g., 4-PBA, TUDCA) will provide an effective therapeutic strategy to reverse airway hyperactivity and blunt remodeling associated with asthma.

Public Health Relevance

Inflammation is a key aspect of airways diseases such as asthma that affects more than 20 million people in the USA. The proposed studies will focus on the effects of inflammation on the coupling between mitochondria and the sarcoplasmic reticulum in human airway smooth muscle (hASM) and the role of this coupling in the hyper reactive 'contractile' state and proliferative 'synthetic' state of hASM.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL126451-04
Application #
9392483
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Lachowicz-Scroggins, Marrah Elizabeth
Project Start
2014-12-22
Project End
2019-11-30
Budget Start
2017-12-01
Budget End
2019-11-30
Support Year
4
Fiscal Year
2018
Total Cost
Indirect Cost
Name
Mayo Clinic, Rochester
Department
Type
DUNS #
006471700
City
Rochester
State
MN
Country
United States
Zip Code
55905
Ryan, Zachary C; Craig, Theodore A; Wang, Xuewei et al. (2018) 1?,25-dihydroxyvitamin D3 mitigates cancer cell mediated mitochondrial dysfunction in human skeletal muscle cells. Biochem Biophys Res Commun 496:746-752
Delmotte, Philippe; Zavaletta, Vanessa A; Thompson, Michael A et al. (2017) TNF? decreases mitochondrial movement in human airway smooth muscle. Am J Physiol Lung Cell Mol Physiol 313:L166-L176
Prakash, Y S; Pabelick, Christina M; Sieck, Gary C (2017) Mitochondrial Dysfunction in Airway Disease. Chest 152:618-626
Aravamudan, Bharathi; Goorhouse, Katelyn J; Unnikrishnan, Ghanashyam et al. (2017) Differential Expression of Estrogen Receptor Variants in Response to Inflammation Signals in Human Airway Smooth Muscle. J Cell Physiol 232:1754-1760
Dogan, Murat; Han, Young-Soo; Delmotte, Philippe et al. (2017) TNF? enhances force generation in airway smooth muscle. Am J Physiol Lung Cell Mol Physiol 312:L994-L1002
Aravamudan, Bharathi; Thompson, Michael; Sieck, Gary C et al. (2017) Functional Effects of Cigarette Smoke-Induced Changes in Airway Smooth Muscle Mitochondrial Morphology. J Cell Physiol 232:1053-1068
Ryan, Zachary C; Craig, Theodore A; Folmes, Clifford D et al. (2016) 1?,25-Dihydroxyvitamin D3 Regulates Mitochondrial Oxygen Consumption and Dynamics in Human Skeletal Muscle Cells. J Biol Chem 291:1514-28
Prakash, Y S (2016) Emerging concepts in smooth muscle contributions to airway structure and function: implications for health and disease. Am J Physiol Lung Cell Mol Physiol 311:L1113-L1140
Delmotte, Philippe; Sieck, Gary C (2015) Interaction between endoplasmic/sarcoplasmic reticulum stress (ER/SR stress), mitochondrial signaling and Ca(2+) regulation in airway smooth muscle (ASM). Can J Physiol Pharmacol 93:97-110