Emerging role of damage-associated molecular patterns derived from mitochondria in inflammation

Glycyrrhetinic acid pretreatment attenuates liver ischemia/reperfusion injury via inhibiting TLR4 signaling cascade in mice

Glycyrrhetinic acid (GA), the main bioactive substances of glycyrrhiza uralensis Fisch, has been reported to exhibit hepatoprotective and anti-inflammatory properties. However, the effects and underlying mechanisms of GA in liver ischemia/reperfusion (I/R) injury remain elusive. In this study, mice were pretreated with GA (100 mg/kg) three times a day by gavage prior to I/R injury, and then hepatic histopathological damages, biochemical parameters and inflammatory molecules were evaluated. We found that mice performed with liver I/R showed a significantly increase in plasma aminotransferase (ALT), aspartate aminotransferase (AST), liver cell apoptosis and infiltration of neutrophils compared with the control group. GA pretreatment notably improved liver function, histopathology of liver tissues, and lowered liver cell apoptosis and infiltration of neutrophils. Besides, further analysis indicated that GA pretreatment reduced I/R-induced expression of extracellular HMGB1, inhibited activation of TLR4 and following phosphorylation of IRAK1, ERK, P38 and NF-κB, and attenuated TNF-α and IL-1β production. These data suggested that GA protected against liver I/R injury through a HMGB1-TLR4 signaling pathway and it might be a promising drug for future clinical use in liver transplantation.

Genomics and the Acute Respiratory Distress Syndrome: Current and Future Directions

The excessive hospital mortality associated with acute respiratory distress syndrome (ARDS) in adults mandates an urgent need for developing new therapies and tools for the early risk assessment of these patients. ARDS is a heterogeneous syndrome with multiple different pathogenetic processes contributing differently in different patients depending on clinical as well as genetic factors. Identifying genetic-based biomarkers holds the promise for establishing effective predictive and prognostic stratification methods and for targeting new therapies to improve ARDS outcomes. Here we provide an updated review of the available evidence supporting the presence of genetic factors that are predictive of ARDS development and of fatal outcomes in adult critically ill patients and that have been identified by applying different genomic and genetic approaches. We also introduce other incipient genomics approximations, such as admixture mapping, metagenomics and genome sequencing, among others, that will allow to boost this knowledge and likely reveal new genetic predictors of ARDS susceptibility and prognosis among critically ill patients.

Enhanced Mitochondrial DNA Repair Resuscitates Transplantable Lungs Donated After Circulatory Death

BACKGROUND

Transplantation of lungs procured after donation after circulatory death (DCD) is challenging because postmortem metabolic degradation may engender susceptibility to ischemia-reperfusion (IR) injury. Because oxidative mitochondrial DNA (mtDNA) damage has been linked to endothelial barrier disruption in other models of IR injury, here we used a fusion protein construct targeting the DNA repair 8-oxoguanine DNA glycosylase-1 (OGG1) to mitochondria (mtOGG1) to determine if enhanced repair of mtDNA damage attenuates endothelial barrier dysfunction after IR injury in a rat model of lung procurement after DCD.

MATERIALS AND METHODS

Lungs excised from donor rats 1 h after cardiac death were cold stored for 2 h after which they were perfused ex vivo in the absence and presence of mt-OGG1 or an inactive mt-OGG1 mutant. Lung endothelial barrier function and mtDNA integrity were determined during and at the end of perfusion, respectively.

RESULTS AND CONCLUSIONS

Mitochondria-targeted OGG1 attenuated indices of lung endothelial dysfunction incurred after a 1h post-mortem period. Oxidative lung tissue mtDNA damage as well as accumulation of proinflammatory mtDNA fragments in lung perfusate, but not nuclear DNA fragments, also were reduced by mitochondria-targeted OGG1. A repair-deficient mt-OGG1 mutant failed to protect lungs from the adverse effects of DCD procurement.

CONCLUSIONS

These findings suggest that endothelial barrier dysfunction in lungs procured after DCD is driven by mtDNA damage and point to strategies to enhance mtDNA repair in concert with EVLP as a means of alleviating DCD-related lung IR injury.

The Immune Functions of α1 Acid Glycoprotein

α1-acid glycoprotein (orosomucoid, AGP) is an Acute Phase Protein produced by liver and peripheral tissues in response to systemic reaction to inflammation. AGP functions have been studied mostly in human, cattle and fish, although the protein has been also found in many mammalian species and birds. AGP fulfils at least two set of functions, which are apparently different from each other but in fact intimately linked. On one hand, AGP is an immunomodulatory protein. On the other hand, AGP is one of the most important binding proteins in plasma and, beside modulating pharmacokinetics and pharmacodynamics of many drugs, it is also able to bind and transport several endogen ligands related to inflammation. The focus of this review is the immunomodulatory activity of AGP. This protein regulates every single event related to inflammation, including binding of pathogens and modulating white blood cells activity throughout the entire leukocyte attacking sequence. The regulation of AGP activity is complex: the inflammation induces not only an increase in AGP serum concentration, but also a qualitative change in its carbohydrate moiety, generating a multitude of glycoforms, each of them with different, and sometimes opposite and contradictory, activities. We also present the most recent findings about the relationship between AGP and adipose tissue: AGP interacts with leptin receptor and, given its immunomodulatory function, it may be included among the potential players in the field of immunometabolism.

Pathophysiological Mechanisms of Nocturia and Nocturnal Polyuria: The Contribution of Cellular Function, the Urinary Bladder Urothelium, and Circadian Rhythm

Alterations to arginine vasopressin (AVP) secretion, the urinary bladder urothelium (UT) and other components of the bladder, and the water homeostasis biosystem may be relevant to the pathophysiology of nocturia and nocturnal polyuria (NP). AVP is the primary hormone involved in water homeostasis. Disruption to the physiological release of AVP or its target effects may relate to several urinary disturbances. Circadian dysregulation and the effects of aging, for example, the development of oxidative stress and mitochondrial dysfunction, may play a role in nocturia voiding symptoms. The urinary bladder UT not only acts as a highly efficient barrier that is maintained during the filling and voiding of the urinary bladder, but is also capable of sensory and transducer function through a network of functional receptors and ion channels that enable reciprocal communication between UT cells and neighboring elements of the bladder mucosa and wall. Functional components of the UT (eg, claudins and receptors or ion channels) play important roles in AVP-mediated water homeostasis. These components and functions involved in water homeostasis, as well as kidney function, may be affected by the aging process, including age-related mitochondrial dysfunction. The characteristics of NP are discussed and the association between NP and circadian rhythm is examined in light of reports that suggest that nocturia should be considered as a type of circadian dysfunction. Many possible pathologic mechanisms that underlie nocturia and NP have been identified. Future studies may provide further insight into pathophysiology with the hope of identifying new treatment modalities.

NLRP6 deficiency aggravates liver injury after allogeneic hematopoietic stem cell transplantation

This study aims to observe the expression and role of NLRP6 in liver injury after allogeneic hematopoietic stem cell transplantation (Allo-HSCT). Allo-HSCT model was established through infusion of 5 × 10⁶ bone marrow mononuclear cells into whole body irradiated mice. On days 7, 14, 21 and 28 after transplantation, the peripheral blood was collected to detect liver function. The liver of the mice was obtained to assess the pathological changes of liver tissues after allo-HSCT by H&E staining and Mason staining. Meanwhile, expression of NLRP6, phosphorylated p38-MAPK and IκBα, caspase-1 and NLRP3 in liver were detected by Western blot. ELISA was used for detection of the level of interleukin (IL)-1β, IL-18, tumor necrosis factor (TNF)-α, IL-6, myeloperoxidase (MPO) and tumor growth factor (TGF)-β1. Increased expression of NLRP6, phosphorylated Iκbα, phosphorylated p38-MAPK, pro-caspase-1, and p20, in liver tissue with injury and fibrosis in mice after allo-HSCT were observed. Meanwhile, the level of IL-1β, IL-18, IL-6 and TNF-α was also increased. However, NLRP6^-/- mice showed more severe liver damage and liver fibrosis after transplantation together with higher level of phosphorylated Iκbα, phosphorylated p38-MAPK, Pro-caspase-1, p20 expression as well as IL-1β, IL-18, IL-6, and TNF-α secretion compared with wide-type. Interestingly, the expression of NLRP3 in the liver of NLRP6^-/- mice was significantly higher than that of wild-type. In conclusion, the expression of NLRP6 in host's liver is associated with liver injury after allo-HSCT. NLRP6 deficiency in host's liver leads to more severe liver damage, indicating a protective role of NLRP6 in host's liver to liver damage after allo-HSCT.

Red Blood Cells Homeostatically Bind Mitochondrial DNA through TLR9 to Maintain Quiescence and to Prevent Lung Injury

RATIONALE

Potentially hazardous CpG-containing cell-free mitochondrial DNA (cf-mtDNA) is routinely released into the circulation and is associated with morbidity and mortality in critically ill patients. How the body avoids inappropriate innate immune activation by cf-mtDNA remains unknown. Because red blood cells (RBCs) modulate innate immune responses by scavenging chemokines, we hypothesized that RBCs may attenuate CpG-induced lung inflammation through direct scavenging of CpG-containing DNA.

OBJECTIVES

To determine the mechanisms of CpG-DNA binding to RBCs and the effects of RBC-mediated DNA scavenging on lung inflammation.

METHODS

mtDNA on murine RBCs was measured under basal conditions and after systemic inflammation. mtDNA content on human RBCs from healthy control subjects and trauma patients was measured. Toll-like receptor 9 (TLR9) expression on RBCs and TLR9-dependent binding of CpG-DNA to RBCs were determined. A murine model of RBC transfusion after CpG-DNA-induced lung injury was used to investigate the role of RBC-mediated DNA scavenging in mitigating lung injury in vivo.

MEASUREMENTS AND MAIN RESULTS

Under basal conditions, RBCs bind CpG-DNA. The plasma-to-RBC mtDNA ratio is low in naive mice and in healthy volunteers but increases after systemic inflammation, demonstrating that the majority of cf-mtDNA is RBC-bound under homeostatic conditions and that the unbound fraction increases during inflammation. RBCs express TLR9 and bind CpG-DNA through TLR9. Loss of TLR9-dependent RBC-mediated CpG-DNA scavenging increased lung injury in vivo.

CONCLUSIONS

RBCs homeostatically bind mtDNA, and RBC-mediated DNA scavenging is essential in mitigating lung injury after CpG-DNA. Our data suggest a role for RBCs in regulating lung inflammation during disease states where cf-mtDNA is elevated, such as sepsis and trauma.

Neuroinflammation in the pathogenesis of axonal Charcot-Marie-Tooth disease caused by lack of GDAP1

Mutations in the GDAP1 mitochondrial outer membrane gene cause Charcot-Marie-Tooth (CMT) neuropathy. Reduction or absence of GDAP1 has been associated with abnormal changes in the mitochondrial morphology and dynamics, oxidative stress and changes in calcium homeostasis. Neuroinflammation has been described in rodent models of genetic demyelinating CMT neuropathies but not in CMT primarily associated with axonopathy. Inflammatory processes have also been related to mitochondrial changes and oxidative stress in central neurodegenerative disorders. Here we investigated the presence of neuroinflammation in the axonal neuropathy of the Gdap1^-/- mice. We showed by transcriptome profile of spinal cord and the in vivo detection of activated phagocytes that the absence of GDAP1 is associated with upregulation of inflammatory pathways. We observed reactive gliosis in spinal cord with increase of the astroglia markers GFAP and S100B, and the microglia marker IBA1. Additionally, we found significant increase of inflammatory mediators such as TNF-α and pERK, and C1qa and C1qb proteins of the complement system. Importantly, we observed an increased expression of CD206 and CD86 as M2 and M1 microglia and macrophage response markers, respectively, in Gdap1^-/- mice. These inflammatory changes were also associated with abnormal molecular changes in synapses. In summary, we demonstrate that inflammation in spinal cord and sciatic nerve, but not in brain and cerebellum, is part of the pathophysiology of axonal GDAP1-related CMT.

Circulating Mitochondrial DNA is Linked to Progression and Prognosis of Epithelial Ovarian Cancer

As peripheral blood contains fluctuated levels of circulating cell-free mitochondrial DNA (ccf mtDNA), we aimed to evaluate ccf mtDNA as a biomarker for diagnosis and prognosis of epithelial ovarian cancer (EOC). In the present study, we recruited 165 EOC patients and 60 healthy women. Quantitative RT-PCR was applied to amplify 79-bp and 230-bp fragments of the mitochondrial 16 s RNA gene in sera of these participants. MtDNA integrity was defined as the ratio of long to short mtDNA fragments. We observed that the levels of mtDNA79 and mtDNA230 were significantly increased (P = .0001), whereas the mtDNA integrity (P = .0001) was decreased in EOC patients compared with those in healthy controls. MtDNA79 showed a sensitivity of 90.3% and a specificity of 81.7% (AUC = 0.900) to discriminate EOC from healthy controls. Moreover, the amounts of mtDNA79 (P = .0001, P = .012, P = .039) and mtDNA230 (P = .0001, P = .042) continuously raised from healthy controls over FIGO I-II to FIGO III and IV, with highest levels of mtDNA79 (P = .0001) and mtDNA230 (P = .0001) in FIGO III and IV. Increasing levels of mtDNA79 (P = .003, P = .0001) and mtDNA230 (P = .041, P = .0001) were also associated with lymph node metastasis and CA125 values. The higher levels of mtDNA79 (P = .0001; HR 3.2, 95%CI:1.6-6.3) and mtDNA230 (borderline P = .048, HR 0.9, 95%CI:0.9-1.0) also correlated with poor patients' overall survival, of which mtDNA79 could act as an independent factor for overall survival. Our data show a significant association of increasing levels of ccf mtDNA with EOC progress and poor prognosis.

Redox (phospho)lipidomics of signaling in inflammation and programmed cell death

In addition to the known prominent role of polyunsaturated (phospho)lipids as structural blocks of biomembranes, there is an emerging understanding of another important function of these molecules as a highly diversified signaling language utilized for intra- and extracellular communications. Technological developments in high-resolution mass spectrometry facilitated the development of a new branch of metabolomics, redox lipidomics. Analysis of lipid peroxidation reactions has already identified specific enzymatic mechanisms responsible for the biosynthesis of several unique signals in response to inflammation and regulated cell death programs. Obtaining comprehensive information about millions of signals encoded by oxidized phospholipids, represented by thousands of interactive reactions and pleiotropic (patho)physiological effects, is a daunting task. However, there is still reasonable hope that significant discoveries, of at least some of the important contributors to the overall overwhelmingly complex network of interactions triggered by inflammation, will lead to the discovery of new small molecule regulators and therapeutic modalities. For example, suppression of the production of AA-derived pro-inflammatory mediators, HXA3 and LTB4, by an iPLA2 γ inhibitor, R-BEL, mitigated injury associated with the activation of pro-inflammatory processes in animals exposed to whole-body irradiation. Further, technological developments promise to make redox lipidomics a powerful approach in the arsenal of diagnostic and therapeutic instruments for personalized medicine of inflammatory diseases and conditions.

Dengue Virus in Bats from Córdoba and Sucre, Colombia

Natural infection of dengue virus (DENV) in bats is an unexplored field in Colombia. To detect the presence of DENV in bats, a descriptive prospective study using a nonprobabilistic sampling was carried out; 286 bats in 12 sites were caught. Sample tissues of different animals were obtained; the RNA was obtained from tissues and a nested-RT-PCR was carried out and detected amplicons of 143 fragment of the NS5 gene were sequenced by the Sanger method. In nonhematophagous bats Carollia perspicillata and Phyllostomus discolor captured in Ayapel and San Carlos (Córdoba), respectively, an amplicon corresponding to NS5 was detected. The amplicons showed a high similarity with serotype-2 dengue virus (DENV-2). This is the first evidence of the DENV-2 genome in bats in from the Colombian Caribbean.

The sensing of mitochondrial DAMPs by non-immune cells

Mitochondria are the source of damage-associated molecular patterns (DAMPs), which are molecules that play a key modulatory role in immune cells. These molecules include proteins and peptides, such as N-formyl peptides and TFAM, as well as lipids, and metabolites such as cardiolipin, succinate and ATP, and also mitochondrial DNA (mtDNA). Recent data indicate that somatic cells sense mitochondrial DAMPs and trigger protective mechanisms in response to these signals. In this review we focus on the well-described effects of mitochondrial DAMPs on immune cells and also how these molecules induce immunogenic responses in non-immune cells. Special attention will be paid to the response to mtDNA.

A toll-like receptor agonist mimicking microbial signal to generate tumor-suppressive macrophages

Switching macrophages from a pro-tumor type to an anti-tumor state is a promising strategy for cancer immunotherapy. Existing agents, many derived from bacterial components, have safety or specificity concerns. Here, we postulate that the structures of the bacterial signals can be mimicked by using non-toxic biomolecules of simple design. Based on bioactivity screening, we devise a glucomannan polysaccharide with acetyl modification at a degree of 1.8 (acGM-1.8), which specifically activates toll-like receptor 2 (TLR2) signaling and consequently induces macrophages into an anti-tumor phenotype. For acGM-1.8, the degree of acetyl modification, glucomannan pattern, and acetylation-induced assembly are three crucial factors for its bioactivity. In mice, intratumoral injection of acGM-1.8 suppresses the growth of two tumor models, and this polysaccharide demonstrates higher safety than four classical TLR agonists. In summary, we report the design of a new, safe, and specific TLR2 agonist that can generate macrophages with strong anti-tumor potential in mice.

Turning tumour promoting macrophages into an anti-tumour phenotype is an attractive therapeutic strategy. Here, the authors develop a polysaccharide-based structure that mimicks pathogen-associated molecular patterns and, by activating the toll-like receptors on macrophage surface, promotes a safe anti-tumour immune response in mouse models.

P2Y2R activation by ATP induces oxLDL-mediated inflammasome activation through modulation of mitochondrial damage in human endothelial cells

Oxidative stress and the related inflammatory responses are closely associated with many diseases including cardiovascular diseases such as atherosclerosis. Especially, mitochondrial damage and inflammasome activation have been reported to be directly involved in atherogenesis. In addition, we previously reported that endothelial cells (ECs) exposed to oxidized LDL (oxLDL) release ATP, which activates P2Y₂R, resulting in the expression of receptors for advanced glycation end products and adhesion molecules that are involved in the pathogenesis of atherosclerosis. Therefore, it is expected that P2Y₂R activation by ATP released under inflammatory conditions may be linked to the inflammasome-mediated pathogenesis of cardiovascular diseases such as atherosclerosis. However, the exact association remains unclear. Thus, in this study, we investigated the role of P2Y₂R in oxLDL-mediated inflammasome activation and the related atherosclerotic pathogenesis in ECs. ECs stimulated with oxLDL demonstrated increased intracellular production and extracellular secretion of ATP. In addition, mitochondrial reactive oxygen species (mtROS) production and mitochondrial DNA (mtDNA) expression and cytosolic release were increased in ECs stimulated with oxLDL or the P2Y₂R agonists ATP and UTP. Moreover, caspase-1 activity and IL-1β production were increased in ECs stimulated with oxLDL, ATP or UTP through the modulation of mtROS production and mtDNA expression, in a P2Y₂R-dependent manner. Furthermore, TLR-9 and NF-κB activation was increased in ECs in response to oxLDL, ATP or UTP, in a mtDNA-dependent manner. Taken together, our findings suggest that P2Y₂R activation by ATP is involved in oxLDL-mediated inflammasome activation and subsequent IL-1β production through the modulation of mtROS-mtDNA induction and the TLR9-NF-κB signaling pathway.

Autoantibodies in Systemic Lupus Erythematosus Target Mitochondrial RNA

The mitochondrion supplies energy to the cell and regulates apoptosis. Unlike other mammalian organelles, mitochondria are formed by binary fission and cannot be directly produced by the cell. They contain numerous copies of a compact circular genome that encodes RNA molecules and proteins involved in mitochondrial oxidative phosphorylation. Whereas, mitochondrial DNA (mtDNA) activates the innate immune system if present in the cytosol or the extracellular milieu, it is also the target of circulating autoantibodies in systemic lupus erythematosus (SLE). However, it is not known whether mitochondrial RNA is also recognized by autoantibodies in SLE. In the present study, we evaluated the presence of autoantibodies targeting mitochondrial RNA (AmtRNA) in SLE. We quantified AmtRNA in an inducible model of murine SLE. The AmtRNA were also determined in SLE patients and healthy volunteers. AmtRNA titers were measured in both our induced model of murine SLE and in human SLE, and biostatistical analyses were performed to determine whether the presence and/or levels of AmtRNA were associated with clinical features expressed by SLE patients. Both IgG and IgM classes of AmtRNA were increased in SLE patients (n = 86) compared to healthy controls (n = 30) (p < 0.0001 and p = 0.0493, respectively). AmtRNA IgG levels correlated with anti-mtDNA-IgG titers (r_s = 0.54, p < 0.0001) as well as with both IgG and IgM against β-2-glycoprotein I (anti-β₂GPI; r_s = 0.22, p = 0.05), and AmtRNA-IgG antibodies were present at higher levels when patients were positive for autoantibodies to double-stranded-genomic DNA (p < 0.0001). AmtRNA-IgG were able to specifically discriminate SLE patients from healthy controls, and were negatively associated with plaque formation (p = 0.04) and lupus nephritis (p = 0.03). Conversely, AmtRNA-IgM titers correlated with those of anti-β₂GPI-IgM (r_s = 0.48, p < 0.0001). AmtRNA-IgM were higher when patients were positive for anticardiolipin antibodies (aCL-IgG: p = 0.01; aCL-IgM: p = 0.002), but AmtRNA-IgM were not associated with any of the clinical manifestations assessed. These findings identify mtRNA as a novel mitochondrial antigen target in SLE, and support the concept that mitochondria may provide an important source of circulating autoantigens in SLE.

Mitochondria Are a Subset of Extracellular Vesicles Released by Activated Monocytes and Induce Type I IFN and TNF Responses in Endothelial Cells

RATIONALE

Extracellular vesicles, including microvesicles, are increasingly recognized as important mediators in cardiovascular disease. The cargo and surface proteins they carry are considered to define their biological activity, including their inflammatory properties. Monocyte to endothelial cell signaling is a prerequisite for the propagation of inflammatory responses. However, the contribution of microvesicles in this process is poorly understood.

OBJECTIVE

To elucidate the mechanisms by which microvesicles derived from activated monocytic cells exert inflammatory effects on endothelial cells.

METHODS AND RESULTS

LPS (lipopolysaccharide)-stimulated monocytic cells release free mitochondria and microvesicles with mitochondrial content as demonstrated by flow cytometry, quantitative polymerase chain reaction, Western Blot, and transmission electron microscopy. Using RNAseq analysis and quantitative reverse transcription-polymerase chain reaction, we demonstrated that both mitochondria directly isolated from and microvesicles released by LPS-activated monocytic cells, as well as circulating microvesicles isolated from volunteers receiving low-dose LPS-injections, induce type I IFN (interferon), and TNF (tumor necrosis factor) responses in endothelial cells. Depletion of free mitochondria significantly reduced the ability of these microvesicles to induce type I IFN and TNF-dependent genes. We identified mitochondria-associated TNFα and RNA from stressed mitochondria as major inducers of these responses. Finally, we demonstrated that the proinflammatory potential of microvesicles and directly isolated mitochondria were drastically reduced when they were derived from monocytic cells with nonrespiring mitochondria or monocytic cells cultured in the presence of pyruvate or the mitochondrial reactive oxygen species scavenger MitoTEMPO.

CONCLUSIONS

Mitochondria and mitochondria embedded in microvesicles constitute a major subset of extracellular vesicles released by activated monocytes, and their proinflammatory activity on endothelial cells is determined by the activation status of their parental cells. Thus, mitochondria may represent critical intercellular mediators in cardiovascular disease and other inflammatory settings associated with type I IFN and TNF signaling.

Plasma Transfusion Products and Contamination with Cellular and Associated Pro-Inflammatory Debris

BACKGROUND

Stored plasma products are widely regarded as being functionally acellular, obviating the need for leukoreduction. We tested the hypothesis that donor plasma is contaminated by leukocytes and platelets, which, after frozen storage, would release cellular debris in quantities sufficient to elicit significant pro-inflammatory responses.

STUDY DESIGN

Samples of never-frozen liquid plasma from 2 regional Level I trauma centers were analyzed for leukocyte and platelet contamination. To determine if the cellular contamination and associated debris found in liquid plasma were at levels sufficient to evoke an innate immune response, known quantities of leukocytes were subjected to a freeze-thaw cycle, added to whole blood, and the magnitude of the inflammatory response was determined by induction of interleukin-6.

RESULTS

Units of never-frozen plasma from 2 regional Level I trauma centers located in Alabama and Louisiana contained significant amounts of leukocyte contamination (Louisiana, n = 22; 17.3 ± 4.5 million vs Alabama, n = 22; 11.3 ± 2.2 million) and platelet contamination (Louisiana, n = 21; 0.86 ± 0.20 billion vs Alabama, n = 22; 1.0 ± 0.3 billion). Cellular debris from as few as 1 million leukocytes induced significant increases in interleukin-6 levels (R² = 0.74; p < 0.0001).

CONCLUSIONS

Stored plasma units from trauma center blood banks were highly contaminated with leukocytes and platelets, at levels more than 15-fold higher than sufficient to elicit ex vivo inflammatory responses. In light of paradigm shifts toward the use of more empiric plasma for treatment of hypovolemia, this study suggests that new manufacturing and quality-control processes are needed to eliminate previously unrecognized cellular contamination present in stored plasma products.

Tumor suppressor function of miR-129-5p in lung cancer

Lung cancer causes severe health problems worldwide and, in China, besides being the principal cause of mortality among urbanites, it is the second leading cause of mortality in the rural population, preceded by hepatocellular carcinoma. Between 80 and 85% of lung cancer is classified as non-small cell lung cancer (NSCLC). The high mobility group box 1 (HMGB1) protein serves an important function in the tumor microenvironment and antitumor response, and may be targeted by microRNA (miR). In the present study, miR-129-5p was identified to target HMGB1 and miR-129-5p exhibited low expression levels in NSCLC tissues. Overexpression of miR-129-5p inhibited cell proliferation and promoted cell apoptosis. In conclusion, the results of the present study suggested the inhibitory function of miR-129-5p and revealed a novel therapeutic target for further investigation.

Platelet-derived extracellular vesicles convey mitochondrial DAMPs in platelet concentrates and their levels are associated with adverse reactions

BACKGROUND

Whereas platelet transfusion is a common medical procedure, inflammation still occurs in a fraction of transfused individuals despite the absence of any apparent infectious agents. Platelets can shed membrane vesicles, called extracellular vesicles (EVs), some of which contain mitochondria (mito+EV). With its content of damage-associated molecular pattern (DAMP), the mitochondrion can stimulate the innate immune system. Mitochondrial DNA (mtDNA) is a recognized DAMP detected in the extracellular milieu in numerous inflammatory conditions and in platelet concentrates. We hypothesized that platelet-derived mitochondria encapsulated in EVs may represent a reservoir of mtDNA.

STUDY DESIGN AND METHODS

Herein, we explored the implication of mito+EVs in the occurrence of mtDNA quantified in platelet concentrate supernatants that induced or did not induce transfusion adverse reactions.

RESULTS

We observed that EVs were abundant in platelet concentrates, and platelet-derived mito+EVs were more abundant in platelet concentrates that induced adverse reactions. A significant correlation (r_s  = 0.73; p < 0.0001) between platelet-derived mito+EV levels and mtDNA concentrations was found. However, there was a nonsignificant correlation between the levels of EVs without mitochondria and mtDNA concentrations (r_s  = -0.11; p = 0.5112). The majority of the mtDNA was encapsulated into EVs.

CONCLUSION

This study suggests that platelet-derived EVs, such as those that convey mitochondrial DAMPs, may be a useful biomarker for the prediction of potential risk of adverse transfusion reactions. Moreover, our work implies that investigations are necessary to determine whether there is a causal pathogenic role of mitochondrial DAMP encapsulated in EVs as opposed to mtDNA in solution.

Immunometabolism of Phagocytes and Relationships to Cardiac Repair

Cardiovascular disease remains the leading cause of death worldwide. Myocardial ischemia is a major contributor to cardiovascular morbidity and mortality. In the case of acute myocardial infarction, subsequent cardiac repair relies upon the acute, and coordinated response to injury by innate myeloid phagocytes. This includes neutrophils, monocytes, macrophage subsets, and immature dendritic cells. Phagocytes function to remove necrotic cardiomyocytes, apoptotic inflammatory cells, and to remodel extracellular matrix. These innate immune cells also secrete cytokines and growth factors that promote tissue replacement through fibrosis and angiogenesis. Within the injured myocardium, macrophages polarize from pro-inflammatory to inflammation-resolving phenotypes. At the core of this functional plasticity is cellular metabolism, which has gained an appreciation for its integration with phagocyte function and remodeling of the transcriptional and epigenetic landscape. Immunometabolic rewiring is particularly relevant after ischemia and clinical reperfusion given the rapidly changing oxygen and metabolic milieu. Hypoxia reduces mitochondrial oxidative phosphorylation and leads to increased reliance on glycolysis, which can support biosynthesis of pro-inflammatory cytokines. Reoxygenation is permissive for shifts back to mitochondrial metabolism and fatty acid oxidation and this is ultimately linked to pro-reparative macrophage polarization. Improved understanding of mechanisms that regulate metabolic adaptations holds the potential to identify new metabolite targets and strategies to reduce cardiac damage through nutrient signaling.

Activation of a TLR9 mediated innate immune response in preeclampsia

Preeclampsia is a multisystemic disorder leading to the development of a placental ischemic microenvironment with a resultant increase in oxidative stress. There is evidence that mitochondrial dysfunction and the innate immune system both play a role in the pathophysiology of this disease. Mitochondrial DAMPs such as mtDNA bind specific pattern recognition receptors such as Toll-like receptor 9 (TLR9) on the endosomal surface of immune cells, in particular neutrophils, subsequently activating them and triggering an innate response. We hypothesised that the exaggerated innate immune response seen in preeclampsia is provoked by dysfunctional mitochondria. Here we provide evidence that TLR9 activity is significantly increased at time of disease in women with preeclampsia. Furthermore, we show activation of neutrophil markers, Calprotectin, Myeloperoxidase (MPO), and IL-8 are significantly increased at time of disease compared to uncomplicated pregnancies. This research supports a potential role of TLR9 activation of an innate immune response evident in preeclampsia which may possibly be initially triggered by dysfunctional mitochondria.

Interleukin-1β Induces mtDNA Release to Activate Innate Immune Signaling via cGAS-STING

Interleukin-1 beta (IL-1β) is a pleiotropic mediator of inflammation and is produced in response to a wide range of stimuli. During infection, IL-1β production occurs in parallel with the onset of innate antimicrobial defenses, but the contribution of IL-1β signaling to cell-intrinsic immunity is not defined. Here, we report that exogenous IL-1β induces interferon regulatory factor 3 (IRF3) activation in human myeloid, fibroblast, and epithelial cells. IRF3 activation by IL-1β is dependent upon the DNA-sensing pathway adaptor, stimulator of interferon genes (STING), through the recognition of cytosolic mtDNA by cyclic guanosine monophosphate (GMP)-AMP synthase (cGAS). IL-1β treatment results in interferon (IFN) production and activation of IFN signaling to direct a potent innate immune response that restricts dengue virus infection. This study identifies a new function for IL-1β in the onset or enhancement of cell-intrinsic immunity, with important implications for cGAS-STING in integrating inflammatory and microbial cues for host defense.

Mitochondrial fission-induced mtDNA stress promotes tumor-associated macrophage infiltration and HCC progression

Tumor-associated macrophages (TAMs) contribute to hepatocellular carcinoma (HCC) progression. However, the molecular mechanism underlying the infiltration of TAMs into HCC microenvironment is largely unclear. Recent studies have reported that alteration of mitochondrial nucleoid structures induces mitochondrial DNA (mtDNA) release into the cytosol, which is recognized as mtDNA stress, and consequently regulates innate immunity. Here we aimed to investigate whether mitochondrial fission induces mtDNA stress and then promotes TAM infiltration and HCC progression. Confocal microscopy and real-time PCR were used to detect cytosolic mtDNA content in HCC cells. The relationship between the expression of mitochondrial fission key regulator dynamin-related protein 1 (Drp1) and the percentage of CD163 (a marker of TAMs)-positive cells was investigated in HCC tissues using immunohistochemistry. Finally, the effect of Drp1 overexpression in HCC cells on recruitment and polarization of TAMs was investigated. Our data showed that increased Drp1 expression was positively correlated with the infiltration of TAMs into HCC tissues. Drp1-mediated mitochondrial fission induced the cytosolic mtDNA stress to enhance the CCL2 secretion from HCC cells by TLR9-mediated NF-κB signaling pathway, and thus promoted the TAM recruitment and polarization. Depleting cytosolic mtDNA using DNase I or blocking TLR9 pathway by TLR9 antagonist, siRNA for TLR9 or p65 in HCC cells with Drp1 overexpression significantly decreased the recruitment and polarization of TAMs. Blocking CCR2 by antagonist significantly reduced TAM infiltration and suppressed HCC progression in mouse model. In conclusion, our findings reveal a novel mechanism of TAM infiltration in HCC by mitochondrial fission-induced mtDNA stress.

Inflammation and fibrosis in murine models of heart failure

Heart failure is a consequence of various cardiovascular diseases and associated with poor prognosis. Despite progress in the treatment of heart failure in the past decades, prevalence and hospitalisation rates are still increasing. Heart failure is typically associated with cardiac remodelling. Here, inflammation and fibrosis are thought to play crucial roles. During cardiac inflammation, immune cells invade the cardiac tissue and modulate tissue-damaging responses. Cardiac fibrosis, however, is characterised by an increased amount and a disrupted composition of extracellular matrix proteins. As evidence exists that cardiac inflammation and fibrosis are potentially reversible in experimental and clinical set ups, they are interesting targets for innovative heart failure treatments. In this context, animal models are important as they mimic clinical conditions of heart failure patients. The advantages of mice in this respect are short generation times and genetic modifications. As numerous murine models of heart failure exist, the selection of a proper disease model for a distinct research question is demanding. To facilitate this selection, this review aims to provide an overview about the current understanding of the pathogenesis of cardiac inflammation and fibrosis in six frequently used murine models of heart failure. Hence, it compares the models of myocardial infarction with or without reperfusion, transverse aortic constriction, chronic subjection to angiotensin II or deoxycorticosterone acetate, and coxsackievirus B3-induced viral myocarditis in this context. It furthermore provides information about the clinical relevance and the limitations of each model, and, if applicable, about the recent advancements in their methodological proceedings.

Relationships Between Ion Channels, Mitochondrial Functions and Inflammation in Human Aging

Aging is often associated with a loss of function. We believe aging to be more an adaptation to the various, and often continuous, stressors encountered during life in order to maintain overall functionality of the systems. The maladaptation of a system during aging may increase the susceptibility to diseases. There are basic cellular functions that may influence and/or are influenced by aging. Mitochondrial function is amongst these. Their presence in almost all cell types makes of these valuable targets for interventions to slow down or even reserve signs of aging. In this review, the role of mitochondria and essential physiological regulators of mitochondria and cellular functions, ion channels, will be discussed in the context of human aging. The origins of inflamm-aging, associated with poor clinical outcomes, will be linked to mitochondria and ion channel biology.

Forms of extracellular mitochondria and their impact in health

Mitochondria play an important role as an intracellular energy plant and signaling organelle. However, mitochondria also exist outside cells where they could mediate cell-to-cell communication, repair and serve as an activator of the immune response. Their effects depend on the mitochondrial state or the form in which it is present, either as a whole functional structure as fragments or only as mitochondrial DNA. Herein, we provide evidence of why extracellular mitochondria and their varying forms are considered regenerative factors or pro-inflammatory activators. Understanding these aspects will provide the base of their use in therapy or as a biomarker of disease severity and prognosis.

Cell-Free Mitochondrial DNA in the CSF: A Potential Prognostic Biomarker of Anti-NMDAR Encephalitis

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune inflammatory brain disease that can develop a variety of neuropsychiatric presentations. However, the underlying nature of its inflammatory neuronal injury remains unclear. Mitochondrial DNA (mtDNA) is recently regarded as a damage-associated molecular pattern molecule (DAMP) that can initiate an inflammatory response. In the presenting study, we aimed to evaluate the levels of cell-free mtDNA in cerebrospinal fluid (CSF) of patients with anti-NMDAR encephalitis and to determine a potential role of cell-free mtDNA in the prognosis of anti-NMDAR encephalitis. A total of 33 patients with NMDAR encephalitis and 17 patients with other non-inflammatory disorders as controls were included in this study. The CSF levels of cell-free mtDNA were measured by quantitative polymerase chain reaction (qPCR). Cytokines including interleukin (IL)-6, IL-10, and tumor necrosis factor alpha (TNF-α) were measured by ELISA. The modified Rankin scale (mRS) score was evaluated for neurologic disabilities. Our data showed that the CSF levels of cell-free mtDNA and inflammation-associated cytokines were significantly higher in the patients with anti-NMDAR encephalitis compared with those in controls. Positive correlations were detected between the CSF levels of cell-free mtDNA and mRS scores of patients with anti-NMDAR encephalitis at both their admission and 6-month follow up. These findings suggest that the CSF level of cell-free mtDNA reflects the underlying neuroinflammatory process in patients with anti-NMDAR encephalitis and correlates with their clinical mRS scores. Therefore, cell-free mtDNA may be a potential prognostic biomarker for anti-NMDAR encephalitis.

Thrombin and the Coag-Inflammatory Nexus in Neurotrauma, ALS, and Other Neurodegenerative Disorders

This review details our current understanding of thrombin signaling in neurodegeneration, with a focus on amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease) as well as future directions to be pursued. The key factors are multifunctional and involved in regulatory pathways, namely innate immune and the coagulation cascade activation, that are essential for normal nervous system function and health. These two major host defense systems have a long history in evolution and include elements and regulators of the coagulation pathway that have significant impacts on both the peripheral and central nervous system in health and disease. The clotting cascade responds to a variety of insults to the CNS including injury and infection. The blood brain barrier is affected by these responses and its compromise also contributes to these detrimental effects. Important molecules in signaling that contribute to or protect against neurodegeneration include thrombin, thrombomodulin (TM), protease activated receptor 1 (PAR1), damage associated molecular patterns (DAMPs), such as high mobility group box protein 1 (HMGB1) and those released from mitochondria (mtDAMPs). Each of these molecules are entangled in choices dependent upon specific signaling pathways in play. For example, the particular cleavage of PAR1 by thrombin vs. activated protein C (APC) will have downstream effects through coupled factors to result in toxicity or neuroprotection. Furthermore, numerous interactions influence these choices such as the interplay between HMGB1, thrombin, and TM. Our hope is that improved understanding of the ways that components of the coagulation cascade affect innate immune inflammatory responses and influence the course of neurodegeneration, especially after injury, will lead to effective therapeutic approaches for ALS, traumatic brain injury, and other neurodegenerative disorders.

Mitochondria: the indispensable players in innate immunity and guardians of the inflammatory response

Mitochondria, the dynamic organelles and power house of eukaryotic cells function as metabolic hubs of cells undergoing continuous cycles of fusion and fission. Recent findings have made it increasingly apparent that mitochondria essentially involved in energy production have evolved as principal intracellular signaling platforms regulating not only innate immunity but also inflammatory responses. Perturbations in mitochondrial dynamics, including fusion/fission, electron transport chain (ETC) architecture and cristae organization have now been actively correlated to modulate metabolic activity and immune function of innate and adaptive immune cells. Several newly identified mitochondrial proteins in mitochondrial outer membrane such as mitochondrial antiviral signaling protein (MAVS) and with mitochondrial DNA acting as danger-associated molecular pattern (DAMP) and mitochondrial ROS generated from mitochondrial sources have potentially established mitochondria as key signaling platforms in antiviral immunity in vertebrates and thereby orchestrating adaptive immune cell activations respectively. A thorough understanding of emerging and intervening role of mitochondria in toll-like receptor-mediated innate immune responses and NLRP3 inflammasome complex activation has gained lucidity in recent years that advocates the imposing functions of mitochondria in innate immunity. Fascinatingly, also how the signals stemming from the endoplasmic reticulum co-operate with the mitochondria to activate the NLRP3 inflammasome is now looked ahead as a stage to unravel as to how different mitochondrial and associated organelle stress responses co-operate to bring about inflammatory consequences. This has also opened avenues of research for revealing mitochondrial targets that could be exploited for development of novel therapeutics to treat various infectious, inflammatory, and autoimmune disorders. Thus, this review explores our current understanding of intricate interplay between mitochondria and other cellular processes like autophagy in controlling mitochondrial homeostasis and regulation of innate immunity and inflammatory responses.

The Role of Mitochondrial Damage-Associated Molecular Patterns in Chronic Neuroinflammation

Mitochondrial dysfunction has been established as a common feature of neurodegenerative disorders that contributes to disease pathology by causing impaired cellular energy production. Mitochondrial molecules released into the extracellular space following neuronal damage or death may also play a role in these diseases by acting as signaling molecules called damage-associated molecular patterns (DAMPs). Mitochondrial DAMPs have been shown to initiate proinflammatory immune responses from nonneuronal glial cells, including microglia and astrocytes; thereby, they have the potential to contribute to the chronic neuroinflammation present in these disorders accelerating the degeneration of neurons. In this review, we highlight the mitochondrial DAMPs cytochrome c (CytC), mitochondrial transcription factor A (TFAM), and cardiolipin and explore their potential role in the central nervous system disorders including Alzheimer's disease and Parkinson's disease, which are characterized by neurodegeneration and chronic neuroinflammation.

Mitochondrial mechanisms and therapeutics in ischaemia reperfusion injury

Acute kidney injury (AKI) remains a major problem in critically unwell children and young adults. Ischaemia reperfusion (IR) injury is a major contributor to the development of AKI in a significant proportion of these cases and mitochondria are increasingly recognised as being central to this process through generation of a burst of reactive oxygen species early in reperfusion. Mitochondria have additionally been shown to have key roles in downstream processes including activation of the immune response, immunomodulation, and apoptosis and necrosis. The recognition of the central role of mitochondria in IR injury and an increased understanding of the pathophysiology that undermines these processes has resulted in identification of novel therapeutic targets and potential biomarkers. This review summarises a variety of therapeutic approaches that are currently under exploration and may have potential in ameliorating AKI in children in the future.

A murine model of acute lung injury identifies growth factors to promote tissue repair and their biomarkers

Type II alveolar epithelial cells (AEC2s) play a crucial role in the regeneration of type I AECs after acute lung injury. The mechanisms underlying the regeneration of AEC2s are not fully understood. To address this issue, here, we investigated a murine model of acute lung injury using mice expressing human Diphtheria Toxin Receptor (DTR) under the control of Lysozyme M promoter (LysM-DTR). DT injection induced the depletion of AEC2s, alveolar macrophages, and bone marrow (BM)-derived myeloid cells in LysM-DTR mice, and the mice died within 6 days after DT injection. Apoptotic AEC2s and bronchiolar epithelial cells appeared at 24 hr, whereas Ki67-positive proliferating cells appeared in the alveoli and bronchioles in the lung of LysM-DTR mice at 72-96 hr after DT injection. Transfer of wild-type BM cells into LysM-DTR mice accelerated the regeneration of AEC2s along with the up-regulation of several growth factors. Moreover, several metabolites were significantly decreased in the sera of LysM-DTR mice compared with WT mice after DT injection, suggesting that these metabolites might be biomarkers to predict AEC2s injury. Together, LysM-DTR mice might be useful to identify growth factors to promote lung repair and the metabolites to predict the severity of lung injury.

Novel Fusion Protein Targeting Mitochondrial DNA Improves Pancreatic Islet Functional Potency and Islet Transplantation Outcomes

Long-term graft survival is an ongoing challenge in the field of islet transplantation. With the growing demand for transplantable organs, therapies to improve organ quality and reduce the incidence of graft dysfunction are of paramount importance. We evaluated the protective role of a recombinant DNA repair protein targeted to mitochondria (Exscien I-III), as a therapeutic agent using a rodent model of pancreatic islet transplantation. We first investigated the effect of therapy on isolated rat islets cultured with pro-inflammatory cytokines (interleukin-1 β, interferon γ, and tumor necrosis factor α) for 48 h and documented a significant reduction in apoptosis by flow cytometry, improved viability by immunofluorescence, and conserved functional potency in vitro and in vivo in Exscien I-III-treated islets. We then tested the effect of therapy in systemic inflammation using a rat model of donor brain death (BD) sustained for a 6-h period. Donor rats were allocated to 4 groups: (non-BD + vehicle, non-BD + Exscien I-III, BD + vehicle, and BD + Exscien I-III) and treated with Exscien I-III (4 mg/kg) or vehicle 30 min after BD induction. Sham (non-BD)-operated animals receiving either Exscien I-III or vehicle served as controls. Islets purified from BD + Exscien I-III-treated donors showed a significant increase in glucose-stimulated insulin release in vitro when compared to islets from vehicle-treated counterparts. In addition, donor treatment with Exscien I-III attenuated the effects of BD and significantly improved the functional potency of transplanted islets in vivo. Our data indicate that mitochondrially targeted antioxidant therapy is a novel strategy to protect pancreas and islet quality from the deleterious effects of cytokines in culture and during the inflammatory response associated with donation after BD. The potential for rapid translation into clinical practice makes Exscien I-III an attractive therapeutic option for the management of brain-dead donors or as an additive to islets in culture after isolation setting.

Temporal profile of serum mitochondrial DNA (mtDNA) in patients with aneurysmal subarachnoid hemorrhage (aSAH)

Aneurysmal subarachnoid hemorrhage (aSAH) is a highly complex disease. Majority of aSAH survivors confront post-SAH complications including cerebral vasospasm (CVS) and delayed cerebral ischemia (DCI) that mainly influence the clinical outcome. Tissue damage during early brain injury may lead to release of damage associated molecular pattern molecules (DAMPs) that may initiate and sustain inflammation during the course of aSAH through activation of pattern recognition receptors. Mitochondrial DNA (mtDNA) due to unmethylated CpG motifs acts as a DAMP via binding to toll-like receptor-9. The aim of this study was to investigate the cell free circulating mtDNA in the systemic circulation of aSAH patients and its association with post-SAH complications and clinical outcome. The DNA was extracted from the serum of 80 aSAH patients at days 1, 3, 5, 7, 9, 11, 13 and from 18 healthy controls. Three representative mitochondrial gene fragments including Cytochrome B (CytB), D-Loop and Cytochrome c oxidase subunit-1 (COX-1) were quantified using a Taqman-probes based qPCR. Levels of mtDNA were quantified from standard curves generated using mtDNA extracted from HepG2 cell mitochondria. Clinical outcome of the patients was assessed by Glasgow outcome scale (GOS) and modified Rankin scale (mRS). Clinical data and post-SAH complications were recorded from patient's record file. Serum D-Loop and COX-1 were significantly elevated early after aSAH and remained high over first 2 weeks. CytB levels were however, initially unchanged but elevated later at day 7 as compared to healthy controls. Cumulative levels measured over two weeks showed significant correlations with post-SAH complications including a negative correlation of D-Loop with pneumonia infection, hydrocephalus and occurrence of epilepsy, a positive correlation of Cyt B with occurrence of CVS and a negative correlation of COX-1 with occurrence of systemic infections and seizures. Cumulative D-Loop values negatively correlated with clinical outcome. Our data suggest that mtDNA may directly or indirectly influence post-SAH complications and clinical outcome.

Mitochondria Released by Apoptotic Cell Death Initiate Innate Immune Responses

In solid organ transplantation, cell death arising from ischemia/reperfusion leads to the release of several damage-associated molecular patterns derived from mitochondria. Mitochondrial damage-associated molecular patterns (mtDAMPs) initiate proinflammatory responses, but it remains unknown whether the mode of cell death affects the inflammatory properties of mitochondria. Murine and human cell lines induced to selectively undergo apoptosis and necroptosis were used to examine the extracellular release of mitochondria during programmed cell death. Mitochondria purified from healthy, apoptotic, and necroptotic cells were used to stimulate macrophage inflammasome responses in vitro and neutrophil chemotaxis in vivo. Inhibition of specific mtDAMPs was performed to identify those responsible for macrophage inflammasome activation. A rat liver transplant model was used to identify apoptotic and necroptotic cell death in graft tissue following ischemia/reperfusion. Both apoptotic and necroptotic cell death occur in parallel in graft tissue. Apoptotic cells released more mitochondria than necroptotic cells. Moreover, mitochondria from apoptotic cells were significantly more inflammatory in terms of macrophage inflammasome activation and neutrophil recruitment. Inhibition of cellular synthesis of cardiolipin, a mitochondria-specific lipid and mtDAMP, significantly reduced the inflammasome-activating properties of apoptosis-derived mitochondria. Mitochondria derived from apoptotic cells are potent activators of innate immune responses, whereas mitochondria derived from healthy or necroptotic cells are significantly less inflammatory. Cardiolipin appears to be a key mtDAMP-regulating inflammasome activation by mitochondria. Methods of inhibiting apoptotic cell death in transplant grafts may be beneficial for reducing graft inflammation and transplant allosensitization.

Propofol inhibits endogenous formyl peptide-induced neutrophil activation and alleviates lung injury

Critically ill patients have a high risk of sepsis. Various studies have demonstrated that propofol has anti-inflammatory effects that may benefit critically ill patients who require anesthesia. However, the mechanism and therapeutic effect remain incompletely understood. Our previous data suggest that propofol can act as a formyl peptide receptor 1 (FPR1) antagonist. Here, we hypothesize that propofol mitigates sepsis-induced acute lung injury (ALI) by inhibiting mitochondria-derived N-formyl peptide-mediated neutrophil activation. Oxidative stress caused by activated neutrophils is involved in the pathogenesis of ALI. In human neutrophils, propofol competitively reduced the release of superoxide and associated reactive oxygen species induced by fMMYALF, a human mitochondria-derived N-formyl peptide, suggesting that propofol effectively suppresses neutrophilic oxidative stress. In addition, propofol significantly inhibited fMMYALF-induced elastase release, chemotaxis, calcium mobilization, and phosphorylation of protein kinase B and mitogen-activated protein kinases. These results indicate that propofol suppresses neutrophil activation by blocking the interaction between endogenous N-formyl peptide and its receptor, FPR1, thus inhibiting downstream signaling. Furthermore, propofol alleviated alveolar wall disruption, edematous changes, and neutrophil infiltration in lipopolysaccharide-induced ALI in mice. Noticeably, propofol improved the survival of sepsis mice. This study indicates that the anti-neutrophil effects of propofol may benefit critically ill septic patients.

Measuring success: utility of biomarkers in sickle cell disease clinical trials and care

Progress in the care of sickle cell disease (SCD) has been hampered by the extreme complexity of the SCD phenotype despite its monogenic inheritance. While epidemiological studies have identified clinical biomarkers of disease severity, with a few exceptions, these have not been routinely incorporated in clinical care algorithms. Furthermore, existing biomarkers have been poorly apt at providing objective parameters to diagnose sickle cell crisis, the hallmark, acute complication of SCD. The repercussions of these diagnostic limitations are reflected in suboptimal care and scarcity of adequate outcome measures for clinical research. Recent progress in molecular and imaging diagnostics has heralded a new era of personalized medicine in SCD. Precision medicine strategies are particularly timely, since molecular therapeutics are finally on the horizon. This chapter will summarize the existing evidence and promising data on biomarkers for clinical care and research in SCD.

Mitochondrial Damage-Associated Molecular Patterns of Injured Axons Induce Outgrowth of Schwann Cell Processes

Activated Schwann cells put out cytoplasmic processes that play a significant role in cell migration and axon regeneration. Following nerve injury, axonal mitochondria release mitochondrial damage-associated molecular patterns (mtDAMPs), including formylated peptides and mitochondrial DNA (mtDNA). We hypothesize that mtDAMPs released from disintegrated axonal mitochondria may stimulate Schwann cells to put out cytoplasmic processes. We investigated RT4-D6P2T schwannoma cells (RT4) in vitro treated with N-formyl-L-methionyl-L-leucyl-phenylalanine (fMLP) or cytosine-phospho-guanine oligodeoxynucleotide (CpG ODN) for 1, 6 and 24 h. We also used immunohistochemical detection to monitor the expression of formylpeptide receptor 2 (FPR2) and toll-like receptor 9 (TLR9), the canonical receptors for formylated peptides and mtDNA, in RT4 cells and Schwann cells distal to nerve injury. RT4 cells treated with fMLP put out a significantly higher number of cytoplasmic processes compared to control cells. Preincubation with PBP10, a selective inhibitor of FPR2 resulted in a significant reduction of cytoplasmic process outgrowth. A significantly higher number of cytoplasmic processes was also found after treatment with CpG ODN compared to control cells. Pretreatment with inhibitory ODN (INH ODN) resulted in a reduced number of cytoplasmic processes after subsequent treatment with CpG ODN only at 6 h, but 1 and 24 h treatment with CpG ODN demonstrated an additive effect of INH ODN on the development of cytoplasmic processes. Immunohistochemistry and western blot detected increased levels of tyrosine-phosphorylated paxillin in RT4 cells associated with cytoplasmic process outgrowth after fMLP or CpG ODN treatment. We found increased immunofluorescence of FPR2 and TLR9 in RT4 cells treated with fMLP or CpG ODN as well as in activated Schwann cells distal to the nerve injury. In addition, activated Schwann cells displayed FPR2 and TLR9 immunostaining close to GAP43-immunopositive regenerated axons and their growth cones after nerve crush. Increased FPR2 and TLR9 immunoreaction was associated with activation of p38 and NFkB, respectively. Surprisingly, the growth cones displayed also FPR2 and TLR9 immunostaining. These results present the first evidence that potential mtDAMPs may play a key role in the induction of Schwann cell processes. This reaction of Schwann cells can be mediated via FPR2 and TLR9 that are canonical receptors for formylated peptides and mtDNA. The possible role for FPR2 and TLR9 in growth cones is also discussed.

Origin and Consequences of Necroinflammation

When cells undergo necrotic cell death in either physiological or pathophysiological settings in vivo, they release highly immunogenic intracellular molecules and organelles into the interstitium and thereby represent the strongest known trigger of the immune system. With our increasing understanding of necrosis as a regulated and genetically determined process (RN, regulated necrosis), necrosis and necroinflammation can be pharmacologically prevented. This review discusses our current knowledge about signaling pathways of necrotic cell death as the origin of necroinflammation. Multiple pathways of RN such as necroptosis, ferroptosis, and pyroptosis have been evolutionary conserved most likely because of their differences in immunogenicity. As the consequence of necrosis, however, all necrotic cells release damage associated molecular patterns (DAMPs) that have been extensively investigated over the last two decades. Analysis of necroinflammation allows characterizing specific signatures for each particular pathway of cell death. While all RN-pathways share the release of DAMPs in general, most of them actively regulate the immune system by the additional expression and/or maturation of either pro- or anti-inflammatory cytokines/chemokines. In addition, DAMPs have been demonstrated to modulate the process of regeneration. For the purpose of better understanding of necroinflammation, we introduce a novel classification of DAMPs in this review to help detect the relative contribution of each RN-pathway to certain physiological and pathophysiological conditions.

Mitochondrial genetic medicine

Inherited mitochondrial DNA (mtDNA) diseases were discovered 30 years ago, and their characterization has provided a new perspective on the etiology of the common metabolic and degenerative diseases, cancer, and aging. The maternally inherited mtDNA contains 37 critical bioenergetic genes that are present in hundreds of copies per cell, but the 'mitochondrial genome' encompasses an additional 1,000-2,000 nuclear DNA (nDNA) mitochondrial genes. The interaction between these two mitochondrial genetic systems provides explanations for phenomena such as the non-Mendelian transmission of the common 'complex' diseases, age-related disease risk and progression, variable penetrance and expressivity, and gene-environment interactions. Thus, mtDNA genetics contributes to the quantitative and environmental components of human genetics that cannot be explained by Mendelian genetics. Because mtDNA is maternally inherited and cytoplasmic, it has fostered the first germline gene therapy, nuclear transplantation. However, effective interventions are still lacking for existing patients with mitochondrial dysfunction.

Attenuation of Lipopolysaccharide-Induced Acute Lung Injury by Cyclosporine-A via Suppression of Mitochondrial DNA

Background

Lipopolysaccharide (LPS) is generally associated with sepsis, which causes multiple system injuries and systemic inflammatory response. Mitochondrial DNA (mtDNA) is of great importance in mediation of inflammation. The aim of this study was to investigate the protective profiles of Cyclosporine-A (CsA) in LPS-induced acute lung injury (ALI) and systemic inflammation by the inhibition of mtDNA and Toll-like receptor.

Material/Methods

Twenty-four C57BL/6 mice were randomly assigned to 4 groups: a sham group (n=6); an experiment group (ALI induced through intraperitoneal injection of 10 mg/ml LPS, n=6); a low-CsA group (injection of 2.5 mg/kg of CsA 15 min after injection of LPS, n=6); and a high-CsA group (injection of 25 mg/kg of CsA 15 min after injection of LPS, n=6). Lung tissue, bronchoalveolar lavage fluid (BALF), and blood samples were collected at 6 h for further analyses.

Results

CsA treatment significantly attenuated LPS-induced lung histopathological changes (P<.05), myeloperoxidase (MPO) activity (P<.05) and lung wet-to-dry weight ratio (P<.05). In addition, injection of CsA decreased total cells (P<.05), neutrophils (P<.05), and total protein (P<.05) in BALF and inflammatory mediators, including tumor necrosis factor-α (TNF-α, P<.05) and interleukin-6 (IL-6, P<.05) in a dose-dependent manner. A significant decrease in mtDNA was observed in the CsA group when compared with controls (P<.05). Furthermore, we demonstrated that there was a significant difference between the high-CsA group and low-CsA group in lung injury score (P<.05), mtDNA (P<.05), and MPO (P<.05).

Conclusions

The evidence from this study suggests that CsA attenuated lung inflammation after LPS injection, and the protective mechanism may at least in part involve decreasing the release of inflammatory cytokines and mtDNA.

Pathophysiology of Sickle Cell Disease

Since the discovery of sickle cell disease (SCD) in 1910, enormous strides have been made in the elucidation of the pathogenesis of its protean complications, which has inspired recent advances in targeted molecular therapies. In SCD, a single amino acid substitution in the β-globin chain leads to polymerization of mutant hemoglobin S, impairing erythrocyte rheology and survival. Clinically, erythrocyte abnormalities in SCD manifest in hemolytic anemia and cycles of microvascular vaso-occlusion leading to end-organ ischemia-reperfusion injury and infarction. Vaso-occlusive events and intravascular hemolysis promote inflammation and redox instability that lead to progressive small- and large-vessel vasculopathy. Based on current evidence, the pathobiology of SCD is considered to be a vicious cycle of four major processes, all the subject of active study and novel therapeutic targeting: ( a) hemoglobin S polymerization, ( b) impaired biorheology and increased adhesion-mediated vaso-occlusion, ( c) hemolysis-mediated endothelial dysfunction, and ( d) concerted activation of sterile inflammation (Toll-like receptor 4- and inflammasome-dependent innate immune pathways). These molecular, cellular, and biophysical processes synergize to promote acute and chronic pain and end-organ injury and failure in SCD. This review provides an exhaustive overview of the current understanding of the molecular pathophysiology of SCD, how this pathophysiology contributes to complications of the central nervous and cardiopulmonary systems, and how this knowledge is being harnessed to develop current and potential therapies.

Mitochondria, Oxytocin, and Vasopressin: Unfolding the Inflammatory Protein Response

Neuroendocrine and immune signaling pathways are activated following insults such as stress, injury, and infection, in a systemic response aimed at restoring homeostasis. Mitochondrial metabolism and function have been implicated in the control of immune responses. Commonly studied along with mitochondrial function, reactive oxygen species (ROS) are closely linked to cellular inflammatory responses. It is also accepted that cells experiencing mitochondrial or endoplasmic reticulum (ER) stress induce response pathways in order to cope with protein-folding dysregulation, in homeostatic responses referred to as the unfolded protein responses (UPRs). Recent reports indicate that the UPRs may play an important role in immune responses. Notably, the homeostasis-regulating hormones oxytocin (OXT) and vasopressin (AVP) are also associated with the regulation of inflammatory responses and immune function. Intriguingly, OXT and AVP have been linked with ER unfolded protein responses (UPR^ER), and can impact ROS production and mitochondrial function. Here, we will review the evidence for interactions between these various factors and how these neuropeptides might influence mitochondrial processes.

Inflammasome: A Double-Edged Sword in Liver Diseases

Inflammasomes have emerged as critical innate sensors of host immune that defense against pathogen infection, metabolism syndrome, cellular stress and cancer metastasis in the liver. The assembly of inflammasome activates caspase-1, which promotes the maturation of interleukin-1β (IL-1β) and interleukin-18 (IL-18), and initiates pyroptotic cell death (pyroptosis). IL-18 exerts pleiotropic effects on hepatic NK cells, priming FasL-mediated cytotoxicity, and interferon-γ (IFN-γ)-dependent responses to prevent the development of liver diseases. However, considerable attention has been attracted to the pathogenic role of inflammasomes in various acute and chronic liver diseases, including viral hepatitis, nanoparticle-induced liver injury, alcoholic and non-alcoholic steatohepatitis. In this review, we summarize the latest advances on the physiological and pathological roles of inflammasomes for further development of inflammasome-based therapeutic strategies for human liver diseases.

Melatonin and cancer: From the promotion of genomic stability to use in cancer treatment

Cancer remains among the most challenging human diseases. Several lines of evidence suggest that carcinogenesis is a complex process that is initiated by DNA damage. Exposure to clastogenic agents such as heavy metals, ionizing radiation (IR), and chemotherapy drugs may cause chronic mutations in the genomic material, leading to a phenomenon named genomic instability. Evidence suggests that genomic instability is responsible for cancer incidence after exposure to carcinogenic agents, and increases the risk of secondary cancers following treatment with radiotherapy or chemotherapy. Melatonin as the main product of the pineal gland is a promising hormone for preventing cancer and improving cancer treatment. Melatonin can directly neutralize toxic free radicals more efficiently compared with other classical antioxidants. In addition, melatonin is able to regulate the reduction/oxidation (redox) system in stress conditions. Through regulation of mitochondrial nction and inhibition of pro-oxidant enzymes, melatonin suppresses chronic oxidative stress. Moreover, melatonin potently stimulates DNA damage responses that increase the tolerance of normal tissues to toxic effect of IR and may reduce the risk of genomic instability in patients who undergo radiotherapy. Through these mechanisms, melatonin attenuates several side effects of radiotherapy and chemotherapy. Interestingly, melatonin has shown some synergistic properties with IR and chemotherapy, which is distinct from classical antioxidants that are mainly used for the alleviation of adverse events of radiotherapy and chemotherapy. In this review, we describe the anticarcinogenic effects of melatonin and also its possible application in clinical oncology.

Common Traits Spark the Mitophagy/Xenophagy Interplay

Selective autophagy contributes to the wellbeing of eukaryotic cells by recycling cellular components, disposing damaged organelles, and removing pathogens, amongst others. Both the quality control process of selective mitochondrial autophagy (Mitophagy) and the defensive process of intracellular pathogen-engulfment (Xenophagy) are facilitated via protein assemblies which have shared molecules, a prime example being the Tank-Binding Kinase 1 (TBK1). TBK1 plays a central role in the immunity response driven by Xenophagy and was recently shown to be an amplifying mechanism in Mitophagy, bring to attention the potential cross talk between the two processes. Here we draw parallels between Xenophagy and Mitophagy, speculating on the inhibitory mechanisms of specific proteins (e.g., the 18 kDa protein TSPO), how the preferential sequestering toward one of the two pathways may undermine the other, and in this way impair cellular response to pathogens and cellular immunity. We believe that an in depth understanding of the commonalities may present an opportunity to design novel therapeutic strategies targeted at both the autonomous and non-autonomous processes of selective autophagy.

Muscle-derived autologous mitochondrial transplantation: A novel strategy for treating cerebral ischemic injury

The available evidence showed that mitochondrial transfer by releasing the extracellular vesicles containing mitochondria from astrocytes to neurons exerted a neuroprotective effect after stroke. Whether extracellular mitochondrial replenishment could rescue the tissues from cerebral ischemic injury still needs to be explored completely. It was hypothesized that the augmentation of mitochondrial damage after cerebral ischemia could be resolved by timely replenishment of exogenous mitochondria. A stroke model of middle cerebral artery occlusion (MCAO) was used in this study to verify this hypothesis. This study found that the number of extracellular mitochondria increased in rat cerebrospinal fluid after MCAO, and a higher proportion of mitochondria were associated with good neurological outcomes. Following 90-min ischemia, autologously derived mitochondria (isolated from autologous pectoralis major) or vehicle alone was infused directly into the lateral ventricles, and the rats were allowed to recover for 4 weeks. A plenty of infused mitochondria were found to be distributed in the boundary and ischemic penumbra areas. Furthermore, the transplantation of mitochondria reduced cellular oxidative stress and apoptosis, attenuated reactive astrogliosis, and promoted neurogenesis after stroke. Moreover, the transplantation of mitochondria decreased brain infarct volume and reversed neurological deficits. The findings suggested that the delivery of mitochondria through the lateral ventricles resulted in their widespread distribution throughout the brain and exerted a neuroprotective effect after ischemia-reperfusion injury.

Mitochondrial peptides cause proinflammatory responses in the alveolar epithelium via FPR-1, MAPKs, and AKT: a potential mechanism involved in acute lung injury

Acute lung injury (ALI) is characterized by alveolar epithelial damage and uncontrolled pulmonary inflammation. Mitochondrial damage-associated molecular patterns (DAMPs), including mitochondrial peptides [ N-formyl peptides (NFPs)], are released during cell injury and death and induce inflammation by unclear mechanisms. In this study, we have investigated the role of mitochondrial DAMPs (MTDs), especially NFPs, in alveolar epithelial injury and lung inflammation. In murine models of ALI, high levels of mitochondrial NADH dehydrogenase 1 in bronchoalveolar lavage fluid (BALF) were associated with lung injury scores and increased formyl peptide receptor (FPR)-1 expression in the alveolar epithelium. Cyclosporin H (CsH), a specific inhibitor of FPR1, inhibited lung inflammation in the ALI models. Both MTDs and NFPs upon intratracheal challenge caused accumulation of neutrophils into the alveolar space with elevated BALF levels of mouse chemokine KC, interleukin-1β, and nitric oxide and increased pulmonary FPR-1 levels. CsH significantly attenuated MTDs or NFP-induced inflammatory lung injury and activation of MAPK and AKT pathways. FPR1 expression was present in rat primary alveolar epithelial type II cells (AECIIs) and was increased by MTDs. CsH inhibited MTDs or NFP-induced CINC-1/IL-8 release and phosphorylation of p38, JNK, and AKT in rat AECII and human cell line A549. Inhibitors of MAPKs and AKT also suppressed MTD-induced IL-8 release and NF-κB activation. Collectively, our data indicate an important role of the alveolar epithelium in initiating immune responses to MTDs released during ALI. The potential mechanism may involve increase of IL-8 production in MTD-activated AECII through FPR-1 and its downstream MAPKs, AKT, and NF-κB pathways.