The PARP inhibitor olaparib exerts beneficial effects in mice subjected to cecal ligature and puncture and in cells subjected to oxidative stress without impairing DNA integrity: A potential opportunity for repurposing a clinically used oncological drug for the experimental therapy of sepsis

Abstract

Poly(ADP-ribose) polymerase (PARP) is involved in the pathogenesis of cell dysfunction, inflammation and organ failure during septic shock. The goal of the current study was to investigate the efficacy and safety of the clinically approved PARP inhibitor olaparib in experimental models of oxidative stress in vitro and in sepsis in vivo. ln mice subjected to cecal ligation a nd puncture (CLP) organ injury markers, circula ting and splenic immune cell distributions, circulating mediators, DNA integrity and survival was measured. ln U937 cells subjected to oxidative stress, cellular bioenergetics, viability and DNA integrity were measured. Olaparib was used to inhibit PARP. The results show that in adult male mice subjected to CLP, olaparib (1-10 mg/kg i.p.) improved multiorgan dysfonction. Olaparib treatrnent reduced the degree of bacterial CFUs. Olaparib attenuated the increases in the levels of several circulating mediators in the plasma. ln the spleen, the number of CD4 + and CDS + lymphocytes were reduced in response to CLP; this reduction was inhibited by olaparib treatrnent. Treg but not Thl 7 lymphocytes increased in response to CLP; these cell populations were reduced in sepsis when the animais received olaparib. The Thl 7 /Treg ratio was lower in CLP-olaparib group than in the CLP control group. Analysis of miRNA expression identifi ed a multitude of changes in spleen and circulating white blood cell miRNA levels after CLP; olaparib treatrnent selectively modulated these responses. Olaparib extended the survival rate of mice subjected to CLP. ln contrast to males, in female mice olaparib did not have significant protective effects in CLP. ln aged mice olaparib exerted beneficial effects that were Jess pronounced than the effects obtained in young adult males. ln in vitro experiments in U937 cells subjected to oxidative stress, olaparib (1-100 µM) inhibited PARP activity, protected against the Joss of cell viability, preserved NAD + levels and improved cellular bioenergetics. ln none of the in vivo or in vitro experiments did we observe any adverse effects of olaparib on

Poly(ADP-Ribose) Polymerase Inhibition in Acute Lung Injury. A Reemerging Concept

“…As discussed previously ( 17 , 81 ), the effective dose of the clinically approved PARP inhibitors in nononcological models is significantly lower than the doses of the same agents in oncology, most likely due to the fact that in nononcological models a partial inhibition of PARP is sufficient to exert therapeutic effects. Thus, it will be possible to find effective doses of olaparib for the therapy of nononcological conditions (in particular, in disease conditions in which the patients do not have any baseline defect in DNA-repair pathways, such as ALI) in which a partial inhibition of PARP exerts beneficial effects without interfering with DNA repair and DNA integrity.…”

“…The preclinical data demonstrating the efficacy of the clinically approved PARP inhibitor olaparib (or 4-(3-{[4-(cyclopropylcarbonyl)piperazin-1-yl]carbonyl}-4-fluorobenzyl)phthalazin-1(2H)-one; marketed as Lynparza) in various experimental models of lung injury and/or various forms of critical illness ( 70 , 72 , 80 , 81 , 83 , 84 ) are especially relevant from the translational standpoint. Olaparib (similar to the PARP inhibitors of other classes) improves pulmonary inflammation, counteracts pulmonary extravasation, reduces oxidative stress, and improves antioxidant status in the lung in various experimental models of ALI ( 70 , 72 , 80 , 83 ) and, importantly, also exerts beneficial effects against the ALI-associated central-nervous-system dysfunction (e.g., cognitive defects) ( 83 ).…”

“…Olaparib also exerts beneficial effects in other animal models that have a significant pulmonary-injury component and/or systemic hyperinflammatory component, including asthma models ( 72 , 74 ), a pulmonary inflammation/emphysema model ( 80 ), and murine models of acute burn injury and pancreatitis ( 84 , 90 ). In a murine model of sepsis (induced by CLP), olaparib improved survival and exerted beneficial effects on inflammatory-mediator production and immune-cell balance, but in this model, no significant pulmonary injury was noted, and olaparib had no effect on the various pulmonary parameters investigated ( 81 ).…”

“…Thus, it will be possible to find effective doses of olaparib for the therapy of nononcological conditions (in particular, in disease conditions in which the patients do not have any baseline defect in DNA-repair pathways, such as ALI) in which a partial inhibition of PARP exerts beneficial effects without interfering with DNA repair and DNA integrity. Indeed, in a CLP model, in which the efficacy and safety of olaparib were simultaneously assessed, olaparib (at the effective dose range of 6–30 mg/kg/d), olaparib beneficially modulated the cytokine and immune status of the animals and improved survival but did not exert any adverse effects on mitochondrial or nuclear DNA integrity in various tissues, including the lung ( 81 ). In a second study, in which the effect of PARP inhibition in a critical illness was assessed not only on efficacy parameters but also on DNA injury, the PARP inhibitor used (INO-1001, 4 mg/kg) provided hemodynamic stabilization in a porcine model of thoracic aortic cross-clamping–induced ischemia/reperfusion, without worsening the DNA damage in peripheral blood lymphocytes ( 91 ).…”

Role of 3-Mercaptopyruvate Sulfurtransferase in the Regulation of Proliferation, Migration, and Bioenergetics in Murine Colon Cancer Cells

“…Cellular bioenergetics was measured by the Extracellular Flux Analysis method as described for various other cell types [10,13]. Cells (15,000/well) were seeded on cell culture microplates and treated with HMPSNE (10, 100, or 300 µM) or its vehicle for 16 h. For analysis of mitochondrial respiration, cells were washed twice with DMEM (pH 7.4) supplemented with L-glutamine (2 mM, Gibco), sodium pyruvate (1 mM, Sigma) and glucose (10 mM, Sigma).…”