Research ArticleInflammationMetabolism Open Access | 10.1172/jci.insight.191649

John Q. Yap,1,2 Azadeh Nikouee,1,2 Matthew Kim,1,2 Quan Cao,3,4 David J. Rademacher,5 Jessie E. Lau,1,2 Ananya Arora,6 Leila Y. Zou,1,2 Yuxiao Sun,7 Luke Szweda,8 Hesham Sadek,8 Sharon Elliot,9 Benjamin Roos,9 Marilyn K. Glassberg,9 Hong-Long Ji,1,2 Xiang Gao,9 Qunfeng Dong,9,10 and Qun Sophia Zang1,2,4,5

1Department of Surgery,

2Burn & Shock Trauma Research Institute,

3Department of Cell and Molecular Physiology,

4Cardiovascular Research Institute, and

5Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

6University of Missouri–Kansas City School of Medicine, Kansas City, Missouri, USA.

7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

8Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, Arizona, USA.

9Department of Medicine and

10Center for Biomedical Informatics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

Address correspondence to: Qun Sophia Zang, Burn & Shock Trauma Research Institute, CTRE 321, Department of Surgery, Stritch School of Medicine, Loyola University Chicago Health Science Campus, 2160 S. 1st Ave, Maywood, Illinois 60153, USA. Email: qzang@luc.edu.

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Find articles by Yap, J. in: PubMed | Google Scholar

1Department of Surgery,

2Burn & Shock Trauma Research Institute,

3Department of Cell and Molecular Physiology,

4Cardiovascular Research Institute, and

5Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

6University of Missouri–Kansas City School of Medicine, Kansas City, Missouri, USA.

7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

8Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, Arizona, USA.

9Department of Medicine and

10Center for Biomedical Informatics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

Address correspondence to: Qun Sophia Zang, Burn & Shock Trauma Research Institute, CTRE 321, Department of Surgery, Stritch School of Medicine, Loyola University Chicago Health Science Campus, 2160 S. 1st Ave, Maywood, Illinois 60153, USA. Email: qzang@luc.edu.

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Find articles by Nikouee, A. in: PubMed | Google Scholar

1Department of Surgery,

2Burn & Shock Trauma Research Institute,

3Department of Cell and Molecular Physiology,

4Cardiovascular Research Institute, and

5Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

6University of Missouri–Kansas City School of Medicine, Kansas City, Missouri, USA.

7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

8Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, Arizona, USA.

9Department of Medicine and

10Center for Biomedical Informatics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

Address correspondence to: Qun Sophia Zang, Burn & Shock Trauma Research Institute, CTRE 321, Department of Surgery, Stritch School of Medicine, Loyola University Chicago Health Science Campus, 2160 S. 1st Ave, Maywood, Illinois 60153, USA. Email: qzang@luc.edu.

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Find articles by Kim, M. in: PubMed | Google Scholar

1Department of Surgery,

2Burn & Shock Trauma Research Institute,

3Department of Cell and Molecular Physiology,

4Cardiovascular Research Institute, and

5Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

6University of Missouri–Kansas City School of Medicine, Kansas City, Missouri, USA.

7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

8Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, Arizona, USA.

9Department of Medicine and

10Center for Biomedical Informatics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

Address correspondence to: Qun Sophia Zang, Burn & Shock Trauma Research Institute, CTRE 321, Department of Surgery, Stritch School of Medicine, Loyola University Chicago Health Science Campus, 2160 S. 1st Ave, Maywood, Illinois 60153, USA. Email: qzang@luc.edu.

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Find articles by Cao, Q. in: PubMed | Google Scholar

1Department of Surgery,

2Burn & Shock Trauma Research Institute,

3Department of Cell and Molecular Physiology,

4Cardiovascular Research Institute, and

5Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

6University of Missouri–Kansas City School of Medicine, Kansas City, Missouri, USA.

7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

8Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, Arizona, USA.

9Department of Medicine and

10Center for Biomedical Informatics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

Address correspondence to: Qun Sophia Zang, Burn & Shock Trauma Research Institute, CTRE 321, Department of Surgery, Stritch School of Medicine, Loyola University Chicago Health Science Campus, 2160 S. 1st Ave, Maywood, Illinois 60153, USA. Email: qzang@luc.edu.

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Find articles by Rademacher, D. in: PubMed | Google Scholar

1Department of Surgery,

2Burn & Shock Trauma Research Institute,

3Department of Cell and Molecular Physiology,

4Cardiovascular Research Institute, and

5Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

6University of Missouri–Kansas City School of Medicine, Kansas City, Missouri, USA.

7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

8Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, Arizona, USA.

9Department of Medicine and

10Center for Biomedical Informatics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

Address correspondence to: Qun Sophia Zang, Burn & Shock Trauma Research Institute, CTRE 321, Department of Surgery, Stritch School of Medicine, Loyola University Chicago Health Science Campus, 2160 S. 1st Ave, Maywood, Illinois 60153, USA. Email: qzang@luc.edu.

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Find articles by Lau, J. in: PubMed | Google Scholar

1Department of Surgery,

2Burn & Shock Trauma Research Institute,

3Department of Cell and Molecular Physiology,

4Cardiovascular Research Institute, and

5Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

6University of Missouri–Kansas City School of Medicine, Kansas City, Missouri, USA.

7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

8Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, Arizona, USA.

9Department of Medicine and

10Center for Biomedical Informatics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

Address correspondence to: Qun Sophia Zang, Burn & Shock Trauma Research Institute, CTRE 321, Department of Surgery, Stritch School of Medicine, Loyola University Chicago Health Science Campus, 2160 S. 1st Ave, Maywood, Illinois 60153, USA. Email: qzang@luc.edu.

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Find articles by Arora, A. in: PubMed | Google Scholar

1Department of Surgery,

2Burn & Shock Trauma Research Institute,

3Department of Cell and Molecular Physiology,

4Cardiovascular Research Institute, and

5Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

6University of Missouri–Kansas City School of Medicine, Kansas City, Missouri, USA.

7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

8Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, Arizona, USA.

9Department of Medicine and

10Center for Biomedical Informatics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

Address correspondence to: Qun Sophia Zang, Burn & Shock Trauma Research Institute, CTRE 321, Department of Surgery, Stritch School of Medicine, Loyola University Chicago Health Science Campus, 2160 S. 1st Ave, Maywood, Illinois 60153, USA. Email: qzang@luc.edu.

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Find articles by Zou, L. in: PubMed | Google Scholar

1Department of Surgery,

2Burn & Shock Trauma Research Institute,

3Department of Cell and Molecular Physiology,

4Cardiovascular Research Institute, and

5Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

6University of Missouri–Kansas City School of Medicine, Kansas City, Missouri, USA.

7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

8Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, Arizona, USA.

9Department of Medicine and

10Center for Biomedical Informatics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

Address correspondence to: Qun Sophia Zang, Burn & Shock Trauma Research Institute, CTRE 321, Department of Surgery, Stritch School of Medicine, Loyola University Chicago Health Science Campus, 2160 S. 1st Ave, Maywood, Illinois 60153, USA. Email: qzang@luc.edu.

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Find articles by Sun, Y. in: PubMed | Google Scholar

1Department of Surgery,

2Burn & Shock Trauma Research Institute,

3Department of Cell and Molecular Physiology,

4Cardiovascular Research Institute, and

5Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

6University of Missouri–Kansas City School of Medicine, Kansas City, Missouri, USA.

7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

8Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, Arizona, USA.

9Department of Medicine and

10Center for Biomedical Informatics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

Address correspondence to: Qun Sophia Zang, Burn & Shock Trauma Research Institute, CTRE 321, Department of Surgery, Stritch School of Medicine, Loyola University Chicago Health Science Campus, 2160 S. 1st Ave, Maywood, Illinois 60153, USA. Email: qzang@luc.edu.

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Find articles by Szweda, L. in: PubMed | Google Scholar

1Department of Surgery,

2Burn & Shock Trauma Research Institute,

3Department of Cell and Molecular Physiology,

4Cardiovascular Research Institute, and

5Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

6University of Missouri–Kansas City School of Medicine, Kansas City, Missouri, USA.

7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

8Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, Arizona, USA.

9Department of Medicine and

10Center for Biomedical Informatics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

Address correspondence to: Qun Sophia Zang, Burn & Shock Trauma Research Institute, CTRE 321, Department of Surgery, Stritch School of Medicine, Loyola University Chicago Health Science Campus, 2160 S. 1st Ave, Maywood, Illinois 60153, USA. Email: qzang@luc.edu.

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Find articles by Sadek, H. in: PubMed | Google Scholar

1Department of Surgery,

2Burn & Shock Trauma Research Institute,

3Department of Cell and Molecular Physiology,

4Cardiovascular Research Institute, and

5Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

6University of Missouri–Kansas City School of Medicine, Kansas City, Missouri, USA.

7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

8Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, Arizona, USA.

9Department of Medicine and

10Center for Biomedical Informatics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

Address correspondence to: Qun Sophia Zang, Burn & Shock Trauma Research Institute, CTRE 321, Department of Surgery, Stritch School of Medicine, Loyola University Chicago Health Science Campus, 2160 S. 1st Ave, Maywood, Illinois 60153, USA. Email: qzang@luc.edu.

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Find articles by Elliot, S. in: PubMed | Google Scholar

1Department of Surgery,

2Burn & Shock Trauma Research Institute,

3Department of Cell and Molecular Physiology,

4Cardiovascular Research Institute, and

5Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

6University of Missouri–Kansas City School of Medicine, Kansas City, Missouri, USA.

7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

8Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, Arizona, USA.

9Department of Medicine and

10Center for Biomedical Informatics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

Address correspondence to: Qun Sophia Zang, Burn & Shock Trauma Research Institute, CTRE 321, Department of Surgery, Stritch School of Medicine, Loyola University Chicago Health Science Campus, 2160 S. 1st Ave, Maywood, Illinois 60153, USA. Email: qzang@luc.edu.

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Find articles by Roos, B. in: PubMed | Google Scholar

1Department of Surgery,

2Burn & Shock Trauma Research Institute,

3Department of Cell and Molecular Physiology,

4Cardiovascular Research Institute, and

5Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

6University of Missouri–Kansas City School of Medicine, Kansas City, Missouri, USA.

7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

8Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, Arizona, USA.

9Department of Medicine and

10Center for Biomedical Informatics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

Address correspondence to: Qun Sophia Zang, Burn & Shock Trauma Research Institute, CTRE 321, Department of Surgery, Stritch School of Medicine, Loyola University Chicago Health Science Campus, 2160 S. 1st Ave, Maywood, Illinois 60153, USA. Email: qzang@luc.edu.

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Find articles by Glassberg, M. in: PubMed | Google Scholar

1Department of Surgery,

2Burn & Shock Trauma Research Institute,

3Department of Cell and Molecular Physiology,

4Cardiovascular Research Institute, and

5Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

6University of Missouri–Kansas City School of Medicine, Kansas City, Missouri, USA.

7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

8Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, Arizona, USA.

9Department of Medicine and

10Center for Biomedical Informatics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

Address correspondence to: Qun Sophia Zang, Burn & Shock Trauma Research Institute, CTRE 321, Department of Surgery, Stritch School of Medicine, Loyola University Chicago Health Science Campus, 2160 S. 1st Ave, Maywood, Illinois 60153, USA. Email: qzang@luc.edu.

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Find articles by Ji, H. in: PubMed | Google Scholar

1Department of Surgery,

2Burn & Shock Trauma Research Institute,

3Department of Cell and Molecular Physiology,

4Cardiovascular Research Institute, and

5Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

6University of Missouri–Kansas City School of Medicine, Kansas City, Missouri, USA.

7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

8Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, Arizona, USA.

9Department of Medicine and

10Center for Biomedical Informatics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

Address correspondence to: Qun Sophia Zang, Burn & Shock Trauma Research Institute, CTRE 321, Department of Surgery, Stritch School of Medicine, Loyola University Chicago Health Science Campus, 2160 S. 1st Ave, Maywood, Illinois 60153, USA. Email: qzang@luc.edu.

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Find articles by Gao, X. in: PubMed | Google Scholar

1Department of Surgery,

2Burn & Shock Trauma Research Institute,

3Department of Cell and Molecular Physiology,

4Cardiovascular Research Institute, and

5Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

6University of Missouri–Kansas City School of Medicine, Kansas City, Missouri, USA.

7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

8Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, Arizona, USA.

9Department of Medicine and

10Center for Biomedical Informatics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

Address correspondence to: Qun Sophia Zang, Burn & Shock Trauma Research Institute, CTRE 321, Department of Surgery, Stritch School of Medicine, Loyola University Chicago Health Science Campus, 2160 S. 1st Ave, Maywood, Illinois 60153, USA. Email: qzang@luc.edu.

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Find articles by Dong, Q. in: PubMed | Google Scholar

1Department of Surgery,

2Burn & Shock Trauma Research Institute,

3Department of Cell and Molecular Physiology,

4Cardiovascular Research Institute, and

5Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

6University of Missouri–Kansas City School of Medicine, Kansas City, Missouri, USA.

7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

8Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, Arizona, USA.

9Department of Medicine and

10Center for Biomedical Informatics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois, USA.

Address correspondence to: Qun Sophia Zang, Burn & Shock Trauma Research Institute, CTRE 321, Department of Surgery, Stritch School of Medicine, Loyola University Chicago Health Science Campus, 2160 S. 1st Ave, Maywood, Illinois 60153, USA. Email: qzang@luc.edu.

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Find articles by Zang, Q. in: PubMed | Google Scholar

Authorship note: Both JQY and AN have greatly contributed to the research design, data collection and analysis, as well as the writing and revision of the manuscript.

Published July 8, 2025 - More info

Published in Volume 10, Issue 13 on July 8, 2025
JCI Insight. 2025;10(13):e191649. https://doi.org/10.1172/jci.insight.191649.
© 2025 Yap et al. This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. Published July 8, 2025 - Version history
Received: January 24, 2025; Accepted: May 28, 2025 View PDF Abstract

Males often experience worse cardiac outcomes than females in sepsis. This study identified pyruvate dehydrogenase kinase 4 (PDK4) as a key mediator of this disparity. PDK4 regulates glucose utilization by inhibiting pyruvate dehydrogenase (PDH) in mitochondria. In a mouse endotoxemia model, a sublethal dose of lipopolysaccharide (LPS, 5 mg/kg) significantly upregulated myocardial PDK4 and induced cardiac dysfunction in males but not females. Cardiac-specific PDK4 overexpression promoted this cardiac dysfunction in both sexes, whereas PDK4 knockout provided protection. In WT males, LPS reduced PDH activity and fatty acid oxidation (FAO) while increasing lactate levels, suggesting a shift toward glycolysis. These effects were exacerbated by PDK4 overexpression but attenuated by knockout. In females, metabolic changes were minimal, aside from reduced FAO in LPS-challenged females overexpressing PDK4. Additionally, a higher LPS dose (8 mg/kg) triggered cardiac dysfunction in females, accompanied by modest upregulation of PDK4, but without changes in PDH or lactate. Dichloroacetate (DCA), restraining PDK-mediated PDH inhibition, improved cardiac function in males but not females during endotoxemia. PDK4 overexpression also exacerbated cardiac mitochondrial damage, reduced mitophagy, and increased oxidative stress and inflammation during endotoxemia — effects that were prevented by PDK4 knockout. These findings suggest that PDK4 drives sex-specific cardiac responses in sepsis.

Graphical Abstract Introduction

Sepsis is a life-threatening condition characterized by organ dysfunction due to a dysregulated host response to infection (1). This leads to systemic inflammation, metabolic dysfunction, and multiorgan failure (1–3). Among various complications of sepsis, sepsis-induced cardiomyopathy (SIC) is a major contributor to hemodynamic instability, impaired fluid imbalances, and inadequate oxygen delivery, which exacerbate systemic organ dysfunction and mortality (4). Despite advancements in antibiotic therapies and critical care techniques, the incidence of sepsis continues to rise (2, 5). Therefore, an in-depth understanding of the pathological mechanisms of sepsis and the development of new therapies are urgently needed. In this context, mechanisms of sex-specific outcomes during sepsis have been underexplored, and previous research has focused predominantly on male subjects. Recently, preclinical and clinical investigations revealed that sepsis outcomes differ between sexes, with females exhibiting less severe SIC compared with their male counterparts (4, 6, 7). These sex-specific differences are likely to involve both sex hormones (8, 9) and non-hormonal factors (10). A better understanding of the molecular mechanisms driving sex-specific outcomes during sepsis will pave the way for the future development of tailored, precise, and effective therapeutic strategies for sepsis patients.

Adverse outcomes in sepsis are frequently associated with disruptions in metabolic homeostasis and accumulation of metabolic intermediates from the breakdown of carbohydrates, lipids, and proteins (11–13). In the early phase of infection, the body’s physiological response demonstrates metabolic plasticity, which enables adaptation to short-term and mild metabolic disruptions. However, in the later stages of sepsis, the disruption of metabolic homeostasis becomes severe and irreversible, resulting in metabolic inflexibility (14, 15). At this stage, the body can no longer produce energy from commonly used metabolites and accumulates toxic substrates that eventually cause organ injury (11, 12, 16–18). Because mitochondria are primarily responsible for generating energy via glucose and fatty acid metabolism, there has been great interest in understanding how defects in mitochondria contribute to sepsis-induced metabolic inflexibility. Specifically, disruption of glucose metabolism due to decreased pyruvate dehydrogenase (PDH) activity has been observed in both clinical samples from sepsis patients (19) and animal models of sepsis (20, 21). PDH is the rate-limiting enzyme in glucose metabolism, converting pyruvate to acetyl coenzyme A (acetyl-CoA), and its activity is regulated by a family of pyruvate dehydrogenase kinases (PDK) within mitochondria (22). The expression of PDK isoforms appears tissue-specific, and PDK4 is one of the most prominent isoforms expressed in the heart (23). PDK4 is upregulated in cardiac tissue from male mice after cecal ligation and puncture–induced (CLP-induced) sepsis (21). Additionally, increased PDK4 was shown in serum samples from pediatric patients with SIC (24). These observations suggest that PDK4 may play a critical role in inducing metabolic inflexibility during SIC. However, whether PDK4 is involved in sex-specific outcomes during SIC has not been studied, and the mechanisms by which PDK4 disrupts mitochondrial properties remain unclear.

Research in our laboratory focuses on unraveling the molecular mechanisms of SIC, with a particular emphasis on the role of cardiac mitochondrial signaling. Our prior investigations showed that sepsis causes deficiencies in mitochondria, leading to the release of harmful danger-associated molecular patterns (DAMPs) that worsen inflammation within the heart (12, 25–27). We further unveiled a causative mechanism behind mitochondrial damage in septic hearts, which involves insufficient and maladaptive autophagy (28–31). Autophagy plays a critical role in maintaining cellular homeostasis under nutrient deprivation or energy stress. Here, we investigated how PDK4 modulates changes in cardiac metabolism and the sequential effects on mitochondrial properties and inflammation during SIC. To do so, we utilized mice with cardiac tissue–specific overexpression and knockout of PDK4. Bacterial endotoxin lipopolysaccharide (LPS) was injected intraperitoneally to simulate the acute inflammatory phase of sepsis. Our findings reveal that PDK4 drives sex-based differences in cardiac outcomes during acute inflammation by altering cardiac metabolism, mitochondrial structure and function, mitochondrial dynamics, mitophagy, oxidative stress, and inflammation. These new results improve our understanding of the molecular basis of metabolic dysfunction in SIC and its sex-specific mechanisms.

Results

Sex-specific cardiac performance and its association with myocardial PDK4 expression in response to endotoxemia. We have previously established a mouse model of endotoxemia, in which we injected LPS intraperitoneally to trigger a severe acute inflammatory response, simulating the initial phase of sepsis (28). Our earlier studies showed that a sublethal dose of LPS challenge, 5 mg/kg, induces cardiac dysfunction in male mice, along with mitochondrial structural damage and functional impairments in the heart (28, 32, 33). The present study was designed to investigate the role of PDK4 in cardiac outcomes following endotoxemia. WT male and female mice were subjected to a 5 mg/kg intraperitoneal LPS challenge, while the sham groups received PBS. Heart tissue was harvested 18 hours after challenge, and PDK4 levels were analyzed in mitochondrial fractions using Western blotting (Figure 1A). Isolation of mitochondria was verified by assessing the mitochondrial marker protein voltage-dependent anion channel (VDAC) in cytosolic and mitochondrial fractions (Supplemental Figure 1A; supplemental material available online with this article; https://doi.org/10.1172/jci.insight.191649DS1). This LPS challenge increased PDK4 protein levels in cardiac mitochondria by approximately 4-fold and 2-fold in male and female mice, respectively (Figure 1A and Supplemental Figure 1B). Using real-time PCR quantification, we observed a similar sex-based difference in PDK4 gene expression in response to LPS; LPS-challenged males exhibited 2-fold higher PDK4 RNA levels compared to LPS-challenged females (Figure 1B).

Figure 1

Association between PDK4 expression and cardiac performance in endotoxemia. In A–C, mice were given LPS challenge (5 mg/kg) or sham treatment and experiments were conducted 18 hours after treatment. (A) PDK4 levels in cardiac mitochondria of WT mice were examined by Western blot. Signals were quantified by densitometry, and results were normalized to total protein (n = 5). (B) PDK4 mRNA expression in cardiac tissue of WT mice was examined by qPCR. Results were normalized to GAPDH (n = 6–9). (C) The cardiac function of WT, PDK4-Tg, and PDK4-KO mice was evaluated by echocardiography. Values of fractional shortening were compared (n = 5–7). (D) PDK4 mRNA expression in cardiac tissue of FCG mice was examined by qPCR. Results were normalized to GAPDH (n = 4–8). The FCG mice have 4 genotypes, including genetic males (XY) with male gonads, genetic males (XY) with female gonads, genetic females (XX) with male gonads, and genetic females (XX) with female gonads. Data are presented as mean ± SEM and were analyzed by 2-way ANOVA. *P < 0.05.

In the same experimental setting, we assessed cardiac performance using echocardiography in mice 18 hours after challenge. Consistent with our previous findings (28, 32, 33), WT male mice exhibited compromised cardiac performance in response to the LPS challenge, as indicated by a significant decrease in fractional shortening (Figure 1C). However, female mice did not show any marked decline in cardiac function in response to the same LPS challenge, suggesting a relationship between PDK4 expression and cardiac function in response to acute inflammatory challenges.

To further determine whether PDK4 drives the sex-dependent cardiac outcomes during endotoxemia, we utilized 2 genetic mouse models: one with cardiac-specific PDK4 overexpression (PDK4-Tg) (34) and another with cardiac-specific PDK4 knockout (PDK4-KO) (35). Echocardiography assessment revealed that the LPS challenge impaired cardiac performance in both male and female PDK4-Tg mice, whereas PDK4 knockout protected cardiac function against the LPS challenge (Figure 1C). PDK4 overexpression and knockout were confirmed via Western blot analysis (Supplemental Figure 1C). Statistical analysis also revealed a marginal interaction (P = 0.053) between sex and PDK4 genotype under the LPS challenge, suggesting that the effects of PDK4 on cardiac function in response to LPS vary by sex. Taken together, these findings suggest that PDK4 may play a previously unrecognized role in mediating sex-specific cardiac performance in response to the acute inflammatory challenge induced by endotoxemia.

Lastly, we explored the mechanisms underlying the sex specificity of cardiac PDK4 expression using the Four Core Genotype (FCG) mouse model (36). This model uniquely differentiates the effects of sex chromosomes (XX versus XY) from those of gonadal sex (testes versus ovaries). In these mice, the Sry gene, which encodes the testis-determining factor, is translocated from the Y chromosome to an autosome. As a result, gonadal sex is no longer dictated by the presence of the Y chromosome. Thus, these FCG mice present four genotypes, including XX and XY gonadal males (XXM, XYM, respectively) and XX and XY gonadal females (XXF, XYF, respectively). We quantified PDK4 mRNA levels in the heart tissue of 17-month-old FCG mice. All mice underwent gonadectomy to eliminate any acute hormonal effects (Figure 1D). We found that XYM mice exhibited the highest PDK4 expression, suggesting that the Y chromosome and long-term exposure to gonadal hormones before gonadectomy may exert lasting organizational effects on gene expression and intrinsically regulate PDK4 expression in male hearts.

PDK4 drives sex-based differences in cardiac metabolism during endotoxemia. PDK4 plays a pivotal role in glucose and fatty acid metabolism by inhibiting the PDH complex in mitochondria (37, 38). As illustrated in Figure 2A, inhibition of PDH by PDK4 would decrease the conversion of pyruvate to acetyl-CoA, leading to an accumulation of pyruvate. Theoretically, this change in metabolism may cause a metabolic shift toward cytosolic glycolysis while increasing reliance on alternative fuel sources, such as fatty acids.

Figure 2

Sex-specific impact of PDK4 on cardiac metabolism. (A) Schematic illustration of PDK4’s proposed role in regulating glucose and fatty acid metabolism. The red arrows indicate metabolic shifts towards FAO in the mitochondria and overproduction of lactate in the cytoplasm due to PDH inhibition by PDK4. In B–G, WT, PDK4-Tg, and PDK4-KO mice were given LPS challenge (5 mg/kg) or sham treatment, and experiments were conducted 18 hours after treatment. (B) PDH activity and (C) lactate levels were measured in heart tissue lysates (n = 5–9 and n = 5–7, respectively). (D) FAO was assessed using FAOblue fluorescence in primary cardiomyocytes isolated from mice (n = 4–5 independent isolations per group). (E) Representative TEM images of cardiomyocytes with lipid droplets indicated by orange arrows. Images are representative of 3 independent isolations per group. Scale bar: 1 μm. (F) Lipid droplet area (n = 48–215 lipid droplets per group) and (G) number (n = 19–37 images per group) were quantified from TEM images using ImageJ software. Data in F and G are from 3 independent isolations per group. Data are presented as mean ± SEM and were analyzed using 2-way ANOVA (*P < 0.05) or Student’s t test (#P < 0.05).

In WT male mice, the LPS challenge significantly decreased PDH activity by 61%, and increased lactate production by 114% (Figure 2, B and C). These results indicate a direct relationship between reduced PDH activity, increased lactate levels, and PDK4 upregulation in male hearts induced by acute inflammation. PDK4 overexpression in male mice significantly reduced PDH activity by 41% and increased lactate levels by 160% compared with WT male mice in the sham condition (Figure 2, B and C). The LPS challenge in PDK4-Tg males further decreased PDH activity. Conversely, PDK4 knockout prevented both the LPS-induced reduction in PDH activity and the LPS-induced increase in lactate production in male mice (Figure 2, B and C). These findings suggest that endotoxemia impairs the heart’s ability to utilize glucose for ATP production through upregulating PDK4 expression in males. This decrease in mitochondrial glucose oxidation also causes a metabolic shift toward cytosolic glycolysis.

Interestingly, we observed different results in female mice under the same experimental conditions. Sham-treated WT female mice exhibited a 29% lower PDH activity compared with their male counterparts (Figure 2B), suggesting sex-specific differences in cardiac glucose utilization between healthy males and females. Following the LPS challenge, no substantial changes in PDH activity or lactate levels were observed in WT female hearts. Furthermore, neither PDK4 overexpression nor PDK4 knockout significantly affected PDH activity or lactate levels (Figure 2, B and C). Statistical analysis further revealed a significant interaction between sex and PDK4 genotype for both PDH activity