Page 59 - M. Immunology

PPARα Activation Leads to Antimicrobial Responses and Inhibits

Pathologic Inflammation during Mycobacterium abscessus Infection

1,2
1,2
Cho Rong Park , Yi Sak Kim , Jin Kyung Kim , Hyeon Ji Kim , Young Jae Kim , Sang Min Jeon , Jin-Man Kim , and Eun-Kyeong
1,2
4
1,2
1,2
1,2
Jo 1,2,3,*
1 Department of Microbiology, Chungnam National University School of Medicine, Daejeon 35015, Republic of Korea
2 Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Republic of Korea
3 Infection Control Convergence Research Center, Chungnam National University, Daejeon 35015, Republic of Korea
4 Department of Pathology, Chungnam National University School of Medicine, Daejeon 35015, Republic of Korea
ABSTRACT BACKGROUND
Peroxisome proliferator-activated receptor α (PPARα) is an attractive target Non-tuberculous mycobacteria (NTM) • Found in nature’s water and soil
for host-directed therapeutics Mycobacterium tuberculosis infection. In this • Most do not cause disease except in
study, we found that administration of gemfibrozil (GEM), a PPARα people with a weak immune system
activator, significantly reduced the in vivo M. abscessus (Mabc) load and • People at risk breath in the organisms
inflammatory response in mice. We examined the effects of PPARα agonist from misty water (for example, in a
GEM on Mabc infection in macrophages and in vivo. GEM showed an shower or hot tub) or from soil. If not
inhibitory effect upon the intracellular growth of Mabc in bone marrow- treated, many people may get a
worsening lung infection
derived macrophages (BMDMs) and human monocyte-derived • Mycobacterium abscessus complex is
macrophages (MDMs). Notably, GEM (100 μM) treatment of BMDMs and rapidly growing, multidrug-resistant,
human MDMs resulted in significant inhibition of the intracellular growth of nontuberculous mycobacteria
Mabc. As a positive control, treatment of Mabc-infected BMDMs with
clarithromycin resulted in a marked inhibitory effect on intracellular growth • Nuclear receptor peroxisome proliferator–activated
of Mabc. GEM-mediated antimicrobial activity was mediated through receptor α (PPAR-α) regulates the expression of
PPARα, since the GEM-induced suppressive effect on intracellular growth genes involved in glucose and lipid metabolism as
well as inflammatory processes.
of Mabc in Ppara+/+ BMDMs was significantly abrogated in Ppara-/-
PPARα has been reported to control the duration
BMDMs. We also showed that GEM treatment inhibited Mabc-induced • and magnitude of the inflammatory response
inflammatory responses in macrophages through PPARα. The inhibitory through its ability to induce expression of genes
effects of GEM on Mabc-mediated Il6 and Ilb expression in Ppara+/+ encoding proteins that are involved in the
BMDMs were significantly abrogated in Ppara-/- BMDMs. Therefore, GEM catabolism of pro-inflammatory lipid mediators.
treatment suppressed Mabc-induced inflammatory response depending on • Through transcriptional control, PPAR-α acts as a
PPARα. These data suggest that GEM treatment increased the key regulator of energy metabolism, and
antimicrobial activity and inhibited pathologic inflammation against mitochondrial and peroxisomal function. However,
in innate host defense
the function of PPAR-α
intracellular Mabc through PPARα. during mycobacterial infection is largely unknown.
RESULTS
Figure1. GEM promotes the antimicrobial response during Mabc infection in a PPARα-dependent manner.

(A) BMDMs were infected with Mabc (MOI of 5) and treated with
gemfibrozil (GEM; 5, 25, or 100 µM) or GW6471 (0.1, 1, or 10 µM)
for 3 dpi. Intracellular survival of Mabc was determined by CFU
assay. (B) BMDMs were infected with Mabc-LuxG13 (MOI of 5) and
treated with GEM (25 or 100 µM) or clarithromycin (CLR; 5 µg/mL)
for 3 dpi. Intracellular survival of Mabc was determined by
bioluminescence analysis. (C) Human MDMs were infected with
Mabc (MOI of 5) and stimulated with GEM (100 µM) for 3 dpi.
Intracellular survival of Mabc was determined. (D) Ppara+/+ and
Ppara-/BMDMs were infected with Mabc (MOI of 5) and treated with
GEM (100 µM) for 3 dpi. Intracellular survival of Mabc was
measured by CFU assay. Data are means±SD of three independent
experiments. * p < 0.05, ** p < 0.01, and *** p < 0.001. Un, untreated;
SC, solvent control; ns, not significant.
Figure2. PPARα activation by GEM regulates the Mabc-mediated expression of inflammatory cytokines in a PPARα-
dependent manner.

(A,B) BMDMs were infected with Mabc (MOI of 5) and treated with
gemfibrozil (GEM; 100 μM) for 6 (B) or 18 h (A). The mRNA levels of
proinflammatory cytokines and chemokines were determined by
qRT-PCR. (C) Ppara +/+ and Ppara -/- BMDMs were infected with
Mabc (MOI of 5) and treated with GEM (100 μM) for 18 h. The
mRNA levels of Il6 and Il1b were measured by qRT-PCR. Data are
means ±SD of three independent experiments. * p < 0.05 and
** p < 0.01. Un, untreated; ns, not significant.

CONCLUSION REFERENCES
Mabc, a rapidly growing NTM, causes serious pulmonary infections in both • Kim et al., Cells. 2020 March; 9(3), 648
immunocompromised individuals. Herein we evaluated the protective effect of
PPARα against Mabc infections. PPARα deficiency led to an increased bacterial • MD Johansen et al., Nat Rev Microbiol. 2020 Jul;18(7):392-407
load and excessive inflammatory response during Mabc infection in vivo and in • Kim et al., J Immunol. 2017 April; 198 (8), 3283-3295
vitro. In this study, we found that administration of GEM exerted a therapeutic
effect and an anti-inflammatory response against Mabc infection in mice. Contact information
Importantly, GEM did not exert a direct antimycobacterial effect against Mabc.
However, GEM treatment showed a significant antimicrobial effect and Cho Rong Park
suppressed inflammatory response against Mabc infection in vitro and in vivo, Department of Microbiology College of Medicine Chungnam National University
depending on PPARα. Collectively, our results suggest that manipulation of Munhwa-ro 266, Jung-gu, Daejeon 35015, Korea
PPARα activation has promising potential as a therapeutic strategy for NTM Tel) +82-42-580-8358 C.P) +82-10-5731-8370 Fax) +82-42-580-8437
disease. E-mail) dd910817@gmail.com