Annexin A1-Mediated Mitochondrial Protection to Ameliorate Surgical Kidney Injury

JAMIE PRIVRATSKY, MD, PHD

Acute kidney injury (AKI) is one of the most common forms of perioperative organ injury occurring in up to 30 percent of postsurgical patients, and it significantly increases morbidity and mortality. A number of vascular and transplant surgeries require interruption of blood flow to the kidney, rendering the kidney ischemic and causing significant metabolic stress. The timing of this kidney insult is known; thus, the possibility exists to intervene to protect the kidney. However, no treatment options exist to prevent or treat postsurgical AKI. The development of kidney protective therapeutics has the potential to greatly improve outcomes in the millions of people who undergo surgical operations and kidney transplants each year.

The long-term goal of Dr. Jamie Privratsky’s laboratory is to develop kidney protective therapeutics to limit postoperative and critical illness AKI. One such therapy could be to limit mitochondrial stress as the kidney is particularly susceptible to mitochondrial stress due to its high metabolic demands. In fact, the kidney has the second highest mitochondrial content of all organs and mitochondrial dysfunction has been highly implicated in the pathogenesis of AKI. As such, the development of mitochondrial protectants that could limit postsurgical and transplant AKI holds considerable promise. Collaborators and previous Duke Anesthesiology Center for Perioperative Organ Protection (CPOP) investigators Zhiquan Zhang, PhD, and Qing Ma, PhD, developed a tripeptide fragment of the human annexin A1 molecule (AnxA1), termed ANXA1sp, which they showed had augmented protective properties against inflammation compared to

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ANXA1sp

SPECIFIC AIM 1:

To determine the role of SIRT3 in ANXA1sp-mediated kidney tubule ATP production. HYPOTHESIS: AnxA1 binds FPR2 in kidney tubular cells to upregulate SIRT3 through peroxisome proliferator-activated receptor gamma coactivator (PGC)1a, which allows for continued oxidative phosphorylation and ATP production. DAPI 8 OHdG SPECIFIC AIM 2: To determine the role of mitochondrial necrosis in ANXA1sp-mediated kidney protection. Citrate synthase HYPOTHESIS: ANXA1sp upregulates SIRT3 to deacetylate CypD and limit FIGURE 1: ANXA1sp-treated mice have lower mitochondrial necrosis to levels of oxidative stress as measured by ameliorate kidney injury. 8-OHdG staining (red) in kidney tissue sections.

ONGOING RESEARCH:

Determine the effects of Annexin A1 on mitochondrial function in myeloid cells and kidney tubular cells

Determine the receptor and signaling pathway through which Annexin A1 modulates mitochondrial protection

Determine the effects of cell-specific SIRT3 deletion on ischemic AKI

other AnxA1 mimetics. In collaboration with CPOP investigator Hagir Suliman, DVM, PhD, Privratsky’s new results reveal that unlike previous research that has shown anti-inflammatory properties of AnxA1 peptide mimetics, ANXA1sp ameliorates ischemic kidney injury in mice by limiting kidney tubular cell death and oxidative stress (Figure 1) and upregulates the mitochondrial protectant sirtuin-3 (SIRT3) (1). Despite the promise of ANXA1sp to limit ischemic kidney injury, the novel mechanism by which ANXA1sp could selectively augment SIRT3 expression and mitochondrial metabolism, and limit kidney cell death are not known. Thus, the objectives of Privratsky’s newly-funded R01 grant are to determine the mechanism through which ANXA1sp augments mitochondrial function and metabolism and limits kidney tubular necrosis. Privratsky will pursue the specific aims (page 48)

FIGURE 2: Proposed with the help of fellow schematic for ANXA1sp- Duke collaborators, mediated kidney Suliman, Sudarshan protection. ANXA1sp is Rajogopal, MD, PhD, hypothesized to increase and Matthew Hirschey,

ATP production and PhD. limit mitochondrially- Once the work is mediated cell death. completed, Privratsky will have defined the novel mechanisms through which ANXA1sp can augment mitochondrial function to limit postsurgical AKI, setting the stage for development of a novel line of mitochondrial protectants. The identification of mitochondrial protectants would not only limit postoperative and transplant AKI but also have broad implications for protection of other organs following surgery and transplantation. BP

FUNDING AWARDED: $1,610,000, FIVE-YEAR R01 GRANT

Funding Source:National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

REFERENCES: 1. Suliman H, Ma Q, Zhang Z, Ren J, Morris BT, Crowley SD, Ulloa L, Privratsky JR. Annexin A1 Tripeptide Mimetic Increases Sirtuin-3 and Augments Mitochondrial Function to Limit Ischemic Kidney Injury. Front Physiol. 2021;12:683098. Epub 2021/07/20. doi: 10.3389/ fphys.2021.683098. PubMed PMID: 34276404; PMCID: PMC8281307.