Abstract Eukaryotic deubiquitinase enzymes (DUBs) play a vital role in maintaining cellular homeostasis by deubiquitinating substrates marked for degradation. Of the ∼100 DUBs discovered in humans, USP8 is unique for its association with human tumors including Cushing’s disease (activating mutation), and solid cancers (genomic overexpression). The mechanisms underlying USP8 in tumorigenesis remain unknown. We first found that USP8 is essential for cell survival using CRISPR-Cas9-mediated homozygous excision and RNA interference. To circumvent obligate lethality, identify the substrates of USP8, and determine pathways dysregulated in human tumors with elevated USP8 activity, we engineered a GFP-auxin inducible degron (AID) at the endogenous USP8 locus in DLD1 cells. Additionally, we assayed both transient and long-term interactors using a promiscuous biotinylator BirA fused to a USP8 lentiviral construct. We performed cell survival, apoptosis assays, immunocytochemistry, western blot, RNAseq, and TMT labeled LC/MS, TUBE and IP-LC/MS study. We found that with auxin activation, DLD1USP8-GFP-AID had >80% reduction in USP8 within 30 minutes. At 6 hours, LC/MS revealed a profound alteration of the proteome and phosphoproteome with suppression of eukaryotic elongational initiation factor-2 (EIF2) signaling. We found that USP8 triggers the Integrated Stress Response (ISR), as measured by an ATF4 reporter assay. Consistently, USP8 overexpression led to a concordant elevation of EIF2 signaling and enrichment of EIF2 signaling peptides in cells expressing the USP8-BirA construct. Moreover, USP8 overexpression in PERK and GCN2 knockout lines suggests that USP8 activates ISR via both the amino acid deprivation (GCN2) and unfolded protein response (PERK) pathways. Taken together, our findings indicate that USP8 activation induces the Integrated Stress Response (ISR) through EIF2α phosphorylation and subsequent activation of the transcription factor ATF4. We propose that tumor cells hijack ISR signaling to promote pro-survival pathways, an effect that can be reversed by pharmacological inhibition of ISR using ISRIB. ISR pathway inhibition or decrease of USP8 activity shows a significant reduction of tumor volume in a syngeneic mouse model. These results reveal targetable downstream pathways of USP8 activation, offering potential therapeutic strategies to improve outcomes in patients with Chusing's disease and solid tumors. Citation Format: Debjani Mandal, Santosh Kumar, Dhruval Bhatt, Yan Li, Kory Johnson, Maric Dragan, Prashant Chittiboina. USP8, a survival gatekeeper turned oncogenic trigger via hyperactivation of the integrated stress response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 5024.

Introduction/Purpose:During the septic cardiomyopathy, the mechanism and relationship to outcome of changes in left ventricular (LV) end diastolic volume (EDV) and ejection fraction (EF) remains obscure. We compared serial changes in LVEF and LVEDV to successive alterations in LV wall ultrastructure, water content, and total mass to investigate whether these measures can explain their basis. Methods:We performed cardiac magnetic resonance imaging at 0,6,18,30,42,54, and 92h post-bacterial challenge in a large-animal model (n=57) that mimics human septic cardiomyopathy. LV tissue was obtained for electron microscopy (EM) upon death and 66h in sacrificed survivors. Results:Between 0-6h post-challenge, LV compliance and EDV reached its greatest decline. Non-survivors (n=18) exhibited significantly greater reductions in LVEDV, along with more myocyte edema, mitochondrial swelling and myofilament fragmentation on EM. This increased tissue damage may explain why non-survivors developed worse LV compliance and a greater decline in LVEDV, which persisted until death. From 6-30h, LVEDV significantly improved to baseline in non-survivors, while survivors experienced ∼20% increases (n=39). Concurrently, there was significant LV mass loss and increases in percent water content that were significantly associated with increases in LVEDV. This is consistent with a passive mechanism for rapidly improving LV compliance and EDV. Full recovery of EF required additional days. We hypothesize the prolonged significant mass loss over 5d reflects an active process for remodeling fragmented myofilaments, eliminating myocyte edema, and mitochondrial swelling, ultimately restoring contractile function. Conclusion:The septic cardiomyopathy constitutes a diffuse ultrastructural injury to myocytes with three phases. Initially, there is a decrease in LVEDV, and EF due to myocyte damage within 6h of bacterial challenge; next, the patient sees a passive LVEDV recovery from 6-30h, where LV mass loss increases relative wall percent water content, which facilitates wall compliance and LVEDV; and lastly, the patient sees mass loss beyond 30h consistent with an active repair mechanism of myocytes, returning systolic function to normal. Therefore, EDV changes are a pathophysiological biomarker for sepsis outcomes. A lower LVEDV indicates persistent unrepairable ultrastructure damage with worsening wall compliance and poorer outcomes. LVEDV dilation is a sign of near-full recovery of ultrastructure injury, augmenting wall compliance and improving outcomes. Clinical Implications:We explain herein why septic cardiomyopathy findings don't have clinical implications like heart failure. Septic patients who exhibit signs of heart failure, low LVEF with high EDVs, are doing well - reflecting mild myocyte injury, effective damaged tissues clearance, increased relative LV wall water content, and compliance. This augments the LVEDV, lowering the LVEF. Septic patients who deteriorate rapidly, contrary to heart failure patients, show high/normal LVEF and low/normal LVEDV. Here, the myocyte damage is severe, leading to insufficient wall repair, and this decreased wall compliance persists, preventing the LV from dilating and making LVEDV low which ultimately raises the LVEF.

Controlled clinical trials investigating ongoing questions about extracorporeal membrane oxygenation (ECMO) for patients with the acute respiratory distress syndrome (ARDS), including what the optimal mechanical ventilation (MV) tidal volume (TV) strategies are and whether ECMO potentiates injurious host responses, are difficult. We therefore conducted a systematic literature search and review to characterize studies investigating ECMO in adult animal lung injury models and to determine whether they inform these questions. A systematic literature search with relevant search terms was conducted of four data bases through 2/2/24. Forty-five studies met inclusion criteria, and most parameters examined were represented similarly in studies with (n = 24) or without (n = 21) severe ARDS PaO2/FiO2s levels (≤ 100 mmHg or > 100 mmHg). Overall, while only 11 studies were published from 1971 to 2005, 5, 8, and 11 were published in subsequent 5-year periods up to 2020 and then 10 through 2/2/24 (Figure 1). Most studies investigated pig or sheep models (n = 32), but since 2016, six studies employed rat models. Eighteen studies administered lung lavage alone or with another lung injury challenge (17 with PaO2/FiO2s ≤ 100) and 9 used oleic acid. Although seven studies administered lipopolysaccharide, very different from clinical ARDS only one used a bacterial and none a viral challenge. Thirty-two studies employed V-V ECMO. The most frequent duration of ECMO investigated was 24 h in 16 studies but only 2 studies investigated longer periods (48 and 96 h). Differences in study questions, methodologies and outcome measures precluded formal meta-analysis. However, overall in studies that compared mechanical ventilation alone (MV) to ECMO groups or that compared differing ECMO groups: in 5 studies ECMO supported tidal volume reductions that approached apneic levels in 2; all but 1 of 10 studies indicated that ECMO with or without TV reductions either did not increase or reduced lung injury measures; 2 studies did while 4 did not find that ECMO aggravated molecular or cellular markers of inflammation; and only 2 studies examined host thrombotic responses with ECMO. Animal models to date have addressed important questions facing ECMO use for ARDS, but ones more closely simulating ARDS in patients appear warranted.

The rubber antioxidant, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6-PPD), as an emerging pollutant, is receiving more and more attention recently. This study investigated the intermolecular interactions of 6-PPD with two key biological macromolecules, human serum albumin (HSA) and alpha-glucosidase (AG), to understand the transport and toxic effects of 6-PPD. Using multiple spectroscopic methods and molecular docking technology, the results demonstrated that 6-PPD could bind to both HSA and AG, thereby inducing fluorescence quenching and conformational changes in both proteins. The binding constants were determined to be (5.93 ± 0.20) × 105 and (3.17 ± 0.15) × 104 L mol-1 respectively for HSA-6-PPD and AG-6-PPD systems at 298 K, revealing strong binding affinities. Molecular docking identified specific binding sites and non-covalent interactions of the two systems. MD and Energy decomposition analysis revealed the dynamics conformational changes of the complexes and identified van der Waals and electrostatic interactions as primary binding drivers for both systems, while polar solvation energy impeded complex formation. TYR161, ILE142, and TYR138 dominated HSA-6-PPD stabilization, whereas AG-6-PPD was driven by hydrophobic interactions with TRP1369 and VAL1373, with ARG1377 incurring substantial desolvation penalties. Synchronous fluorescence and circular dichroism spectroscopy indicated that 6-PPD binding did not disrupt the microenvironment of Tyr and Trp residues in HSA and AG, while induced structural alterations in HSA and AG that could affect their physiological function. In-vitro tests showed that 6-PPD inhibited AG activity in a dose-dependent manner, with an IC50 of 8.22 ± 0.44 μmol L-1. ADMET and PASS online tools was used to predict physicochemical properties and multiorgan toxicity. This work provided insights into the transport and molecular toxicity of 6-PPD, highlighting the adverse biological effects associated with this common rubber additive.

Disruption of nicotinamide adenine dinucleotide (NAD) biosynthesis and function during infection may impair host defenses and aggravate inflammatory and oxidative organ injury. Increasingly, studies are investigating whether niacin or NAD metabolite treatment is beneficial in infection and sepsis animal models. We examined whether this preclinical experience supports clinical trials. A systematic review of three data bases was conducted through 2/29/2024 and a meta-analysis was performed comparing niacin or NAD metabolite treatment to control in adult animal models employing microbial challenges. Fifty-six studies met inclusion criteria, with 24 published after 2019. Most studies employed mouse (n = 40 studies) or rat (n = 12) models and administered either a bacterial toxin (n = 28) or bacterial (n = 19) challenge. Four and three studies employed viral or fungal challenges respectively. Studies investigated an NAD metabolite alone (n = 44), niacin alone (n = 9), or both (n = 3), usually administered before or within 24h after challenge (n = 50). Only three and four studies included standard antimicrobial support or started treatment > 24h after challenge respectively. In similar patterns with differing animal types (p ≥ 0.06), compared to control across those studies investigating the parameter, niacin or NAD treatment decreased the odds ratio of mortality [95% confidence interval (CI)] [0.28 (0.17, 0.49)] and in blood or tissue increased antioxidant levels [standardized mean differences (95%CI)] (SMD) [3.61 (2.20,5.02)] and decreased levels of microbes [− 2.44 (− 3.34, − 1.55)], histologic and permeability organ injury scoring [− 1.62 (− 2.27, − 0.98) and − 1.31(− 1.77, − 0.86) respectively], levels of TNFα, IL-6 and IL-1β [− 2.47 (− 3.30, − 1.64), − 3.17 (− 4.74, − 1.60) and − 8.44 (− 12.4, − 4.5) respectively] and myeloperoxidase (MPO) [− 1.60 (− 2.06, − 1.14)], although with significant, primarily quantitative heterogeneity for each (I2 ≥ 53%, p < 0.01) except MPO. Treatment increased blood or tissue NAD+ levels and decreased chemical organ injury measures and oxidation markers but differently comparing species (p ≤ 0.05). Only 2 and 9 survival studies described power analyses or animal randomization respectively and no study described treatment or non-histologic outcome measure blinding. Among survival studies, Egger’s analysis (p = 0.002) suggested publication bias. While suggestive, published animal studies do not yet support clinical trials testing niacin and NAD metabolite treatment for infection and sepsis. Animal studies simulating clinical conditions and with randomized, blinded designs are needed to investigate this potentially promising therapeutic approach.

IntroductionBecause prior immune checkpoint inhibitor (ICI) therapy in cancer patients presenting with COVID-19 may affect outcomes, we investigated the beta-coronavirus, murine hepatitis virus (MHV)-1, in a lethal pneumonia model in the absence (Study 1) or presence of prior programmed cell death ligand-1 (PD-L1) antibody (PD-L1mAb) treatment (Study 2). MethodsIn Study 1, animals were inoculated intratracheally with MHV-1 or vehicle and evaluated at day 2, 5, and 10 after infection. In Study 2, uninfected or MHV-1-infected animals were pretreated intraperitoneally with control or PD-L1-blocking antibodies (PD-L1mAb) and evaluated at day 2 and 5 after infection. Each study examined survival, physiologic and histologic parameters, viral titers, lung immunophenotypes, and mediator production.ResultsStudy 1 results recapitulated the pathogenesis of COVID-19 and revealed increased cell surface expression of checkpoint molecules (PD-L1, PD-1), higher expression of the immune activation marker angiotensin converting enzyme (ACE), but reduced detection of the MHV-1 receptor CD66a on immune cells in the lung, liver, and spleen. In addition to reduced detection of PD-L1 on all immune cells assayed, PD-L1 blockade was associated with increased cell surface expression of PD-1 and ACE, decreased cell surface detection of CD66a, and improved oxygen saturation despite reduced blood glucose levels and increased signs of tissue hypoxia. In the lung, PD-L1mAb promoted S100A9 but inhibited ACE2 production concomitantly with pAKT activation and reduced FOXO1 levels. PD-L1mAb promoted interferon-γ but inhibited IL-5 and granulocyte-macrophage colony-stimulating factor (GM-CSF) production, contributing to reduced bronchoalveolar lavage levels of eosinophils and neutrophils. In the liver, PD-L1mAb increased viral clearance in association with increased macrophage and lymphocyte recruitment and liver injury. PD-L1mAb increased the production of virally induced mediators of injury, angiogenesis, and neuronal activity that may play role in COVID-19 and ICI-related neurotoxicity. PD-L1mAb did not affect survival in this murine model. DiscussionIn Study 1 and Study 2, ACE was upregulated and CD66a and ACE2 were downregulated by either MHV-1 or PD-L1mAb. CD66a is not only the MHV-1 receptor but also an identified immune checkpoint and a negative regulator of ACE. Crosstalk between CD66a and PD-L1 or ACE/ACE2 may provide insight into ICI therapies. These networks may also play role in the increased production of S100A9 and neurological mediators in response to MHV-1 and/or PD-L1mAb, which warrant further study. Overall, these findings support observational data suggesting that prior ICI treatment does not alter survival in patients presenting with COVID-19.

Mechanisms to control the immune response are important to pathogen evasion and host defense. Gram-negative bacteria are common pathogens that can activate host immune responses through their outer membrane component, LPS. Macrophage activation by LPS induces cell signals that promote hypoxic metabolism, phagocytosis, Ag presentation, and inflammation. Nicotinamide (NAM) is a vitamin B3 derivative and precursor in the formation of NAD, which is a required cofactor in cellular function. In this study, treatment of human monocyte-derived macrophages with NAM promoted posttranslational modifications that antagonized LPS-induced cell signals. Specifically, NAM inhibited AKT and FOXO1 phosphorylation, decreased p65/RelA acetylation, and promoted p65/RelA and hypoxia-inducible transcription factor-1α (HIF-1α) ubiquitination. NAM also increased prolyl hydroxylase domain 2 (PHD2) production, inhibited HIF-1α transcription, and promoted the formation of the proteasome, resulting in reduced HIF-1α stabilization, decreased glycolysis and phagocytosis, and reductions in NOX2 activity and the production of lactate dehydrogenase A. These NAM responses were associated with increased intracellular NAD levels formed through the salvage pathway. NAM and its metabolites may therefore decrease the inflammatory response of macrophages and protect the host against excessive inflammation but potentially increase injury through reduced pathogen clearance. Continued study of NAM cell signals in vitro and in vivo may provide insight into infection-associated host pathologies and interventions.

Determining how prior immune checkpoint inhibitor (ICI) therapy influences outcomes in cancer patients presenting with COVID‐19 is essential for patient management but must account for confounding variables.

SummaryChloroquine (CQ) and hydroxychloroquine (HCQ) have been used as antiviral agents for the treatment of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV2) infection. We performed a systematic review to examine whether prior clinical studies that compared the effects of CQ and HCQ to a control for the treatment of non‐SARS‐CoV2 infection supported the use of these agents in the present SARS‐CoV2 outbreak. PubMed, EMBASE, Scopus and Web of Science (PROSPERO CRD42020183429) were searched from inception through 2 April 2020 without language restrictions. Of 1766 retrieved reports, 18 studies met our inclusion criteria, including 17 prospective controlled studies and one retrospective study. CQ or HCQ were compared to control for the treatment of infectious mononucleosis (EBV, n = 4), warts (human papillomavirus, n = 2), chronic HIV infection (n = 6), acute chikungunya infection (n = 1), acute dengue virus infection (n = 2), chronic HCV (n = 2), and as preventive measures for influenza infection (n = 1). Survival was not evaluated in any study. For HIV, the virus that was most investigated, while two early studies suggested HCQ reduced viral levels, four subsequent ones did not, and in two of these CQ or HCQ increased viral levels and reduced CD4 counts. Overall, three studies concluded CQ or HCQ were effective; four concluded further research was needed to assess the treatments' effectiveness; and 11 concluded that treatment was ineffective or potentially harmful. Prior controlled clinical trials with CQ and HCQ for non‐SARS‐CoV2 viral infections do not support these agents' use for the SARS‐CoV2 outbreak.

Background. Staphylococcus aureus (SA) bacterial pneumonia is a common cause of sepsis in intensive care units. Immune checkpoint inhibitors (CPIs) that target programmed cell death protein 1 (PD-1) and its ligand (PD-L1) have been proposed for the treatment of sepsis. However, in our systematic review of sepsis preclinical models, none of the models examined CPIs in pneumonia. Methods. Mice were inoculated intratracheally with vehicle control, low dose (LD)- or high dose (IID)-SA. Immune cell recruitment and checkpoint molecule expression were examined at 4, 24, and 48 hours after infection. Infected animals, treated with control or anti-PD-L1 antibodies, were assessed for survival, bacterial burden, lung immunophenotypes, and mediator production. Results. LD-SA and HD-SA produced lethality of 15% and 70%, respectively, by 168 hours. At 24 hours, LD-infected animals exhibited increased lung monocyte PD-L1 expression (P = .0002) but lower bacterial counts (P = .0002) compared with HD animals. By 48 hours, either infection induced lung neutrophil and macrophage PD-L1 expression (P < .0001). Anti-PD-L1 treatment at the time of infection and at 24 hours following infection with low to high doses of SA reduced PD-L1 detection but did not affect survival or bacterial clearance. Conclusions. Anti-PD-L1 therapy did not alter survival in this pneumonia model. Preclinical studies of additional common pathogens and septic foci are needed.

Anti-toxin agents for severe B. anthracis infection will only be effective if they add to the benefit of the two mainstays of septic shock management, antibiotic therapy and titrated hemodynamic support. Both of these standard therapies could negate benefits related to anti-toxin treatment. At present, three anthrax anti-toxin antibody preparations have received US Food and Drug Administration (FDA) approval: Raxibacumab, Anthrax Immune Globulin Intravenous (AIGIV) and ETI-204. Each agent is directed at the protective antigen component of lethal and edema toxin. All three agents were compared to placebo in antibiotic-treated animal models of live B. anthracis infection, and Raxibacumab and AIGIV were compared to placebo when combined with standard hemodynamic support in a 96 h canine model of anthrax toxin-associated shock. However, only AIG has actually been administered to a group of infected patients, and this experience was not controlled and offers little insight into the efficacy of the agents. To provide a broader view of the potential effectiveness of these agents, this review examines the controlled preclinical experience either in antibiotic-treated B. anthracis models or in titrated hemodynamic-supported toxin-challenged canines. The strength and weaknesses of these preclinical experiences are discussed.

Abstract Background Lethal B. anthracis infection produces high proinflammatory peptidoglycan (PGN) burdens in hosts. We investigated whether the lethality and inflammation anthrax PGN can produce are related. Methods At 6 h before and the start of 24 h anthrax PGN infusions, rats (n = 198) were treated with diluent (controls) or one of three IV-doses of either hydrocortisone (125, 12.5 or 1.25 mg/kg) or TNF-soluble receptor (TNFsr; 2000, 1000 or 333 μg/kg), non-selective and selective anti-inflammatory agents, respectively. Results Compared to controls, hydrocortisone 125 and 12.5 mg/kg each decreased 7-day lethality (p ≤ 0.004). Hydrocortisone 125 mg/kg decreased IL-1β, IL-6, TNFα, MCP, MIP-1α, MIP-2, RANTES and nitric oxide (NO) blood levels at 4 and 24 h after starting PGN (except MCP at 24 h). Each decrease was significant at 4 h (except MIP-1α that was significant at 24 h) (p ≤ 0.05). Similarly, hydrocortisone 12.5 mg/kg decreased each measure at 4, 24 and 48 h (except TNFα at 24 h and MIP-1α at 24 and 48 h and NO at 48 h). Decreases were significant for IL-6 and NO at 4 h and RANTES at 48 h (p ≤ 0.05). Hydrocortisone 1.25 mg/kg had non-significant effects. Each TNFsr dose decreased lethality but non-significantly. However, when doses were analyzed together, TNFsr decreased lethality in a potential trend (p = 0.16) and IL-6 and NO significantly at 4 h (p = 0.05). Conclusions Peptidoglycan-stimulated host inflammation may contribute to B. anthracis lethality.

The most important findings here are edema toxin’s potent adenyl cyclase activity can interfere with hypoxic pulmonary vasoconstriction, an action that could worsen hypoxemia during invasive anthrax infection with lung involvement. These findings, coupled with other studies showing that lethal toxin can disrupt pulmonary vascular integrity, indicate that both toxins can contribute to pulmonary pathophysiology during infection. In combination, these investigations provide a further basis for the use of antitoxin therapies in patients with worsening invasive anthrax disease.

Although lethal toxin (LT) and edema toxin (ET) contribute to lethality during Bacillus anthracis infection, whether they increase vascular permeability and the extravascular fluid accumulation characterizing this infection is unclear. We employed an isolated perfused Sprague-Dawley rat lung model to investigate LT and ET effects on pulmonary vascular permeability. Lungs (n ≥ 6 per experimental group) were isolated, ventilated, suspended from a force transducer, and perfused. Lung weight and pulmonary artery (Ppa) and left atrial pressures were measured over 4 h, after which pulmonary capillary filtration coefficients (Kf.c) and lung wet-to-dry weight ratios (W/D) were determined. When compared with controls, LT increased Ppa over 4 h and Kf.c and W/D at 4 h (P < 0.0001). ET decreased Ppa in a significant trend (P = 0.09) but did not significantly alter Kf.c or W/D (P ≥ 0.29). Edema toxin actually blocked LT increases in Ppa but not LT increases in Kf.c and W/D. When Ppa was maintained at control levels, LT still increased Kf.c and W/D (P ≤ 0.004). Increasing the dose of each toxin five times significantly increased and a toxin-directed monoclonal antibody decreased the effects of each toxin (P ≤ 0.05). Two rho-kinase inhibitors (GSK269962 and Y27632) decreased LT increases in Ppa (P ≤ 0.02) but actually increased Kf.c and W/D in LT and control lungs (P ≤ 0.05). A vascular endothelial growth factor receptor inhibitor (ZM323881) had no significant effect (P ≥ 0.63) with LT. Thus, LT but not ET can increase pulmonary vascular permeability independent of increased Ppa and could contribute to pulmonary fluid accumulation during anthrax infection. However, pulmonary vascular dilation with ET could disrupt protective hypoxic vasoconstriction. NEW & NOTEWORTHY The most important findings from the present study are that Bacillus anthracis lethal toxin increases pulmonary artery pressure and pulmonary permeability independently in the isolated rat lung, whereas edema toxin decreases the former and does not increase permeability. Each effect could be a basis for organ dysfunction in patients with this lethal infection. These findings further support the need for adjunctive therapies that limit the effects of both toxins during infection.

Although serum from patients with Parkinson’s disease contains elevated levels of numerous pro-inflammatory cytokines including IL-6, TNF, IL-1β, and IFNγ, whether inflammation contributes to or is a consequence of neuronal loss remains unknown1. Mutations in parkin, an E3 ubiquitin ligase, and PINK1, a ubiquitin kinase, cause early onset Parkinson’s disease2,3. Both PINK1 and parkin function within the same biochemical pathway and remove damaged mitochondria from cells in culture and in animal models via mitophagy, a selective form of autophagy4. The in vivo role of mitophagy, however, is unclear, partly because mice that lack either PINK1 or parkin have no substantial Parkinson’s-disease-relevant phenotypes5–7. Mitochondrial stress can lead to the release of damage-associated molecular patterns (DAMPs) that can activate innate immunity8–12, suggesting that mitophagy may mitigate inflammation. Here we report a strong inflammatory phenotype in both Prkn −/− and Pink1 −/− mice following exhaustive exercise and in Prkn −/−;mutator mice, which accumulate mutations in mitochondrial DNA (mtDNA)13,14. Inflammation resulting from either exhaustive exercise or mtDNA mutation is completely rescued by concurrent loss of STING, a central regulator of the type I interferon response to cytosolic DNA15,16. The loss of dopaminergic neurons from the substantia nigra pars compacta and the motor defect observed in aged Prkn −/−;mutator mice are also rescued by loss of STING, suggesting that inflammation facilitates this phenotype. Humans with mono- and biallelic PRKN mutations also display elevated cytokines. These results support a role for PINK1- and parkin-mediated mitophagy in restraining innate immunity. Acute and chronic mitochondrial stress in mice require PINK1 and parkin to restrain STING-mediated innate immunity.

Although edema toxin (ETx) and lethal toxin (LTx) contribute to Bacillus anthracis shock and lethality, the mechanisms underlying their cardiovascular effects are unclear. We have previously shown that ETx but not LTx inhibited phenylephrine-stimulated contraction of aortic rings prepared from healthy rats and that adefovir, a selective inhibitor of ETx cAMP production, blocked this effect. Here, we examined arterial function in rats that received 24-h ETx or LTx infusions. Compared with control rats, ETx reduced mean arterial pressure (MAP) and survival over 48 h (P ≤ 0.0003) and increased plasma cAMP at 4, 24, and 48 h (P < 0.0001) and nitric oxide (NO) at 24 and 48 h (P ≤ 0.01). Compared with control animals, at 24- and 48-h phenylephrine stimulation of aortic rings from ETx animals produced decreased maximal contractile force (MCF; P = 0.05 and 0.006) and in vivo phenylephrine infusion in ETx animals produced decreased proportional increases in MAP (P < 0.0001 and P = 0.05). In ETx-treated animals, compared with placebo-treated animals, adefovir treatment prevented all lethality (P = 0.01), increased MAP (P ≤ 0.0001), decreased plasma and aortic tissue cAMP at 24 and 48 h, respectively (P ≤ 0.03), and plasma NO at both times (P ≤ 0.004), and increased phenylephrine-stimulated increases in MCF in aortic rings and MAP in vivo at 48 h (P = 0.02). LTx decreased MAP and survival also, but it did not alter the response to phenylephrine of MCF in aortic rings prepared from LTx animals or of MAP in vivo. In conclusion, in rats, hypotension and lethality are associated with reduced arterial contractile function with ETx but not LTx and adefovir improves ETx-induced hypotension and lethality.NEW & NOTEWORTHY The most important aspects of the present study are the findings that 1) in vivo challenge with anthrax edema but not lethal toxin depresses arterial contractile function measured both ex vivo and in vivo and 2) adefovir inhibits the effects of edema toxin on arterial hypotension and improves survival with lethal dose of edema toxin challenge.

Although anthrax immune globulin (AIG) improved survival in antibiotic-treated Bacillus anthracis-challenged animal models, whether it adds to the benefit of conventional hemodynamic support for B. anthracis toxin-associated shock is unknown.