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

Sepsis is a life-threatening condition with high hospital mortality. Elevated mortality has also been observed in patients after hospital discharge due to post-sepsis syndrome (PSS). The etiology of PSS is still not entirely known, but it involves inflammation. Plasma extracellular vesicles (EVs) are recognized as a unique mechanism of intercellular communication in inflammatory processes. It has been reported that EV microRNA (miRNA) production during the acute sepsis phase may persist until after disease resolution and is associated with PSS. We employed mass spectrometry and qPCR analysis to determine the protein and miRNA composition of plasma-derived EVs of 36 patients during sepsis-related hospitalization, immediately after ICU discharge (post-sepsis), and three, six, twelve, and up to 36 months post-sepsis. We determined that patients’ immune system cells were the primary EV source. Fifteen differentially expressed EV miRNAs (DEmiRs) were identified in samples from septic patients compared to the control group. Predictive analyses revealed that these DEmiRs could influence inflammation by modulating pathways mediated by NF-κB, STAT3, and TLR4 signaling activation. Thirteen miRNAs (-15b-5p,-16-5p,-20a-5p,-25-3p,-27a-3p,-29a-3p,-30d-5p,-93-5p,-146a-5p,-148a-3p,-191-5p,-195-5p,-223-3p) were downregulated in the death group compared to the survivor group, making them candidate prognostic markers of ICU survival. One year after ICU discharge, the expression of miR-21-5p and miR-195-5p were decreased in the survivor group. The miRNAs identified in the present study represent potential biomarkers for the survival prognosis of post-sepsis patients.

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