LRRK2 maintains mitochondrial homeostasis and regulates innate immune responses to Mycobacterium tuberculosis
- Texas A&M Health Science Center, United States
- Texas A&M University College of Veterinary Medicine and Biomedical Sciences, United States
Abstract
The Parkinson's Disease (PD)-associated gene leucine-rich repeat kinase (LRRK2) has been studied extensively in the brain. However, several studies have established that mutations in LRRK2 confer susceptibility to mycobacterial infection, suggesting LRRK2 also controls immunity. We demonstrate that loss of LRRK2 in macrophages induces elevated basal levels of type I interferons (IFN) and interferon stimulated genes (ISGs) and causes blunted interferon responses to mycobacterial pathogens and cytosolic nucleic acid agonists. Altered innate immune gene expression in Lrrk2 knockout (KO) macrophages is driven by a combination of mitochondrial stresses, including oxidative stress from low levels of purine metabolites and DRP1-dependent mitochondrial fragmentation. Together, these defects promote mtDNA leakage into the cytosol and chronic cGAS engagement. While Lrrk2 KO mice can control Mycobacterium tuberculosis (Mtb) replication, they have exacerbated inflammation and lower ISG expression in the lungs. These results demonstrate previously unappreciated consequences of LRRK2-dependent mitochondrial defects in controlling innate immune outcomes.
Data availability
All data generated or analyzed during this study are included in the manuscript and supporting files. Source data files have been provided for Figures 1 and 5.
Article and author information
Author details
Funding
Michael J. Fox Foundation for Parkinson's Research (M1801235)
- Robert O Watson
National Institute of Allergy and Infectious Diseases (R21AI40004)
- Robert O Watson
National Institute of General Medical Sciences (R35GM133720)
- Kristin L Patrick
Parkinson's Disease Foundation
- Chi G Weindel
National Institutes of Health (5T32OD011083-10)
- Krystal J Vail
Michael J. Fox Foundation for Parkinson's Research (12185)
- Robert O Watson
National Institute of Allergy and Infectious Diseases (1R01AI12551)
- Robert O Watson
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Russell E Vance, University of California, Berkeley, United States
Ethics
Animal experimentation: This study followed the recommendations in the Guide for the Care and Use of Laboratory Animals by the National Research Council. All animals were housed, bred, and studied at Texas A&M Health Science Center using protocols reviewed and approved by the institutional animal care and use committee (IACUC) of Texas A&M University (protocol #2018-0125).
Version history
- Received: August 14, 2019
- Accepted: February 14, 2020
- Accepted Manuscript published: February 14, 2020 (version 1)
- Version of Record published: April 15, 2020 (version 2)
Copyright
© 2020, Weindel et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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LRRK2 maintains mitochondrial homeostasis and regulates innate immune responses to Mycobacterium tuberculosis
eLife 9:e51071.
https://doi.org/10.7554/eLife.51071
Further reading
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- Cell Biology
- Immunology and Inflammation
Cytokine polyfunctionality is a well-established concept in immune cells, especially T cells, and their ability to concurrently produce multiple cytokines has been associated with better immunological disease control and subsequent effectiveness during infection and disease. To date, only little is known about the secretion dynamics of those cells, masked by the widespread deployment of mainly time-integrated endpoint measurement techniques that do not easily differentiate between concurrent and sequential secretion. Here, we employed a single-cell microfluidic platform capable of resolving the secretion dynamics of individual PBMCs. To study the dynamics of poly-cytokine secretion, as well as the dynamics of concurrent and sequential polyfunctionality, we analyzed the response at different time points after ex vivo activation. First, we observed the simultaneous secretion of cytokines over the measurement time for most stimulants in a subpopulation of cells only. Second, polyfunctionality generally decreased with prolonged stimulation times and revealed no correlation with the concentration of secreted cytokines in response to stimulation. However, we observed a general trend towards higher cytokine secretion in polyfunctional cells, with their secretion dynamics being distinctly different from mono-cytokine-secreting cells. This study provided insights into the distinct secretion behavior of heterogenous cell populations after stimulation with well-described agents and such a system could provide a better understanding of various immune dynamics in therapy and disease.
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- Immunology and Inflammation
- Medicine
Background:
Prinflammatory extracellular chromatin from neutrophil extracellular traps (NETs) and other cellular sources is found in COVID-19 patients and may promote pathology. We determined whether pulmonary administration of the endonuclease dornase alfa reduced systemic inflammation by clearing extracellular chromatin.
Methods:
Eligible patients were randomized (3:1) to the best available care including dexamethasone (R-BAC) or to BAC with twice-daily nebulized dornase alfa (R-BAC + DA) for seven days or until discharge. A 2:1 ratio of matched contemporary controls (CC-BAC) provided additional comparators. The primary endpoint was the improvement in C-reactive protein (CRP) over time, analyzed using a repeated-measures mixed model, adjusted for baseline factors.
Results:
We recruited 39 evaluable participants: 30 randomized to dornase alfa (R-BAC +DA), 9 randomized to BAC (R-BAC), and included 60 CC-BAC participants. Dornase alfa was well tolerated and reduced CRP by 33% compared to the combined BAC groups (T-BAC). Least squares (LS) mean post-dexamethasone CRP fell from 101.9 mg/L to 23.23 mg/L in R-BAC +DA participants versus a 99.5 mg/L to 34.82 mg/L reduction in the T-BAC group at 7 days; p=0.01. The anti-inflammatory effect of dornase alfa was further confirmed with subgroup and sensitivity analyses on randomised participants only, mitigating potential biases associated with the use of CC-BAC participants. Dornase alfa increased live discharge rates by 63% (HR 1.63, 95% CI 1.01–2.61, p=0.03), increased lymphocyte counts (LS mean: 1.08 vs 0.87, p=0.02) and reduced circulating cf-DNA and the coagulopathy marker D-dimer (LS mean: 570.78 vs 1656.96 μg/mL, p=0.004).
Conclusions:
Dornase alfa reduces pathogenic inflammation in COVID-19 pneumonia, demonstrating the benefit of cost-effective therapies that target extracellular chromatin.
Funding:
LifeArc, Breathing Matters, The Francis Crick Institute (CRUK, Medical Research Council, Wellcome Trust).
Clinical trial number:
