Mitochondrial DNA Copy Number and Lung Function among...

Mitochondrial DNA Copy Number and

Lung Function among People with or at

Risk of HIV

Jing Sun, Sarath Raju, Damani A. Piggott, Jacquie Astemborski, Robert

Brown, Dan E. Arking, Gregory D. Kirk

10th International Workshop on HIV & Aging

© 2014, Johns Hopkins University. All rights reserved.

© 2014, Johns Hopkins University. All rights reserved.© 2014, Johns Hopkins University. All rights reserved.© 2014, Johns Hopkins University. All rights reserved.©2015, Johns Hopkins University. All rights reserved.©2017, Johns Hopkins University. All rights reserved.

DisclosureNo conflict of interest in relation to this presentation.



Background

• PLWH experience accelerated lung function decline and higher prevalence / incidence of COPD than people without HIV.

• Mitochondria play a critical role in human disease and aging.

• Mitochondrial DNA copy number (mtDNA CN) in blood as a biomarker of mitochondrial function in multiple comorbid diseases



Mitochondrial DNA Copy Number & HIV infection

Sun, et al, JID, 2018



mtDNA CN and All-cause Mortality by

HIV Status



Background

• PLWH experience accelerated lung function decline and higher incidence of COPD than people without HIV.

• Mitochondria play a critical role in human disease and aging

• Mitochondrial DNA copy number (mtDNA CN) in blood as a biomarker of mitochondrial function in multiple comorbid diseases

• Studies on mtDNA CN and COPD have yielded inconsistent results.



Population & Methods

• SHIELD cohort

• Study of HIV Infection in the Etiology of Lung Disease (SHIELD)

• Consortium of 2 on-going HIV cohorts in Baltimore

• Participants had semi-annual visits to have surveys and physical examinations. Blood samples and spirometry were collected during visits

• COPD definition

• Forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) ratio<70%



DNA extraction from buffy coat

qPCR (TaqMan chemistry)Cycle threshold (Ct) for ND1 (mitochondrial probe)

Ct for RPPH1 (nuclear DNA probe)

QC:Outlier of triplicate was removed if SD of delta Ct>0.5

If SD was still>0.5 after outlier was removed then the entire sample was removed (re-ran later)Removed replicate with Ct value for ND1>30 (mitochondrial probe)

Removed replicate with Ct value for RPPH1>5 SD from mean (nuclear DNA probe)Removed replicates with delta Ct>3 SD from the plate mean

Standardize mtDNA CN within cohortAdjustment for plating effect & pipetting order

Compute delta Ct between ND1 & RPPH1

Final standardize phenotype by white blood cell counts & platelet counts

Mitochondrial DNA Copy Number Measurement Flowchart



Baseline Characteristics

variables Overall (N=501)

HIV-(N=329)

HIV+ (N=172)

P-value

Male gender, N(%) 321 (64.1) 214 (65.1) 107 (62.2) 0.56

Black, N(%) 464 (92.6) 296 (90.0) 168 (97.7) <0.01

Age over 50, N(%) 318 (63.5) 211 (64.1) 107 (62.2) 0.70

Baseline smoking status, N(%) 376 (75.1) 252 (76.6) 124 (72.1) 0.28

Baseline smoking pack per year≥40, N(%)

85 (17) 55 (16.7) 30 (17.5) 0.80

Current IDU, N(%) 107 (21.4) 75 (22.8) 32 (18.6) 0.30



Correlates of COPD

*high mtDNA CN=4th (highest) quartile of mtDNA CN within the population

The association was stronger among HIV- than HIV+

Crude estimate Adjusted estimate

OR P-value OR P-value

High mtDNA CN* 1.67 0.02 1.97 <0.01

HIV 1.14 0.12

Female 0.49 0.03

Black 0.88 0.77

Current smoker 1.56 0.1

Smoking pack years≥40 1.75 0.04

Age 1.03 0.12

Current IDU 1.63 0.05



mtDNA CN, HIV Infection, and Lung

FunctionHIV negative HIV positiveΔ

Slope¶

(change /year)

SE P Slope¶

(change

/year).

SE P

Age<50

years

Interaction between

mtDNA CN and time

(age)

0.00001 0.0003 0.97 -0.0007 0.0007 0.26

FEV1/FVC

(low mtDNA CN)

0.0001 0.0008 0.88 -0.0007 0.001 0.65

FEV1/FVC

(high mtDNA CN)

0.0001 0.0008 0.87 -0.001 0.002 0.35

Age≥50 Interaction between

mtDNA CN and time

(age)

-0.0005 0.0002 0.02 -0.0002 0.0003 0.55

FEV1/FVC

(low mtDNA CN)

-0.0016 0.0005 0.002 -0.0027 0.0008 <0.001

FEV1/FVC

(high mtDNA CN)

-0.0021 0.0005 <0.001 -0.0029 0.0008 <0.001

mtDNA CN and COPD severity in ARIC

*predicted mtDNA CN adjusted for age, sex, ethnic, study center, education, family income, cigarette smoking status, years of smoking, drinking status, and ethanol intake



mtDNA CN and COPD in SHIELD

* mtDNA CN adjusted for age, sex, race (black vs. non-black), pack year of cigarette≥40, current smoker, current IDU

Conclusion

• mtDNA CN was associated with higher odds of COPD among a population exposed to smoking.

• This association is likely due to a mitochondrial compensatory response to hypoxemia in COPD.

• Mitochondrial function might be impaired among PLWH and was not able to provide as much compensatory response under stress.

Acknowledgement

• SHIELD participants and study staff

• Mentor: Gregory Kirk

• Collaborators: Sarath Raju, Damani A. Piggott, Jacquie Astemborski, Robert Brown, Dan E. Arking

Thank you!

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