Mitochondrial dysfunction causes Ca2+ overload and ECM degradation-mediated muscle damage in C. elegans

Inhibition of Pyruvate Dehydrogenase Kinase 4 Protects Cardiomyocytes from lipopolysaccharide-Induced Mitochondrial Damage by Reducing Lactate Accumulation

Mitochondrial dysfunction is considered one of the major pathogenic mechanisms of sepsis-induced cardiomyopathy (SIC). Pyruvate dehydrogenase kinase 4 (PDK4), a key regulator of mitochondrial metabolism, is essential for maintaining mitochondrial function. However, its specific role in SIC remains unclear. To investigate this, we established an in vitro model of septic cardiomyopathy using lipopolysaccharide (LPS)-induced H9C2 cardiomyocytes. Our study revealed a significant increase in PDK4 expression in LPS-treated H9C2 cardiomyocytes. Inhibiting PDK4 with dichloroacetic acid (DCA) improved cell survival, reduced intracellular lipid accumulation and calcium overload, and restored mitochondrial structure and respiratory capacity while decreasing lactate accumulation. Similarly, Oxamate, a lactate dehydrogenase inhibitor, exhibited similar effects to DCA in LPS-treated H9C2 cardiomyocytes. To further validate whether PDK4 causes cardiomyocyte and mitochondrial damage in SIC by promoting lactate production, we upregulated PDK4 expression using PDK4-overexpressing lentivirus in H9C2 cardiomyocytes. This resulted in elevated lactate levels, impaired mitochondrial structure, and reduced mitochondrial respiratory capacity. However, inhibiting lactate production reversed the mitochondrial dysfunction caused by PDK4 upregulation. In conclusion, our study highlights the pathogenic role of PDK4 in LPS-induced cardiomyocyte and mitochondrial damage by promoting lactate production. Therefore, targeting PDK4 and its downstream product lactate may serve as promising therapeutic approaches for treating SIC.

Can antimony contamination in soil undermine the ecological contributions of earthworms?

As antimony (Sb) has been increasingly used in manufacturing industries (e.g., alloy, polymer and electronics industries), Sb contamination in the soil environment becomes widely reported and has drawn growing attention due to the toxicity of Sb to living organisms. Whether soil-dwelling organisms can tolerate Sb toxicity and maintain their ecological functions remains poorly understood. Using a cosmopolitan, ecologically important earthworm species (Eisenia fetida) as an ideal model organism, we examine the effects of Sb on the physiological, molecular and behavioural responses of earthworms to different levels of Sb contamination in soil (0, 10, 50, 100, 250 and 500 mg/kg). We found that earthworms could tolerate heavy Sb contamination (100 mg/kg) by boosting their antioxidant defence (POD and GST) and immune systems (ACP) so that their body weight and survival rate were sustained (c.f. control). However, these systems were compromised under extreme Sb contamination (500 mg/kg), leading to mortality. As such, earthworms exhibited avoidance behaviour to escape from the Sb-contaminated soil, implying the loss of their ecological contributions to the environment (e.g., increase in soil aeration and maintenance of soil structure). By measuring various types of biomarkers along a concentration gradient, this study provides a mechanistic understanding of how earthworms resist or succumb to Sb toxicity. Since extreme Sb contamination in soil (>100 mg/kg) is rarely found in nature, we are optimistic that the health and performance of earthworms are not influenced by Sb in most circumstances, but regular monitoring of Sb in soil is recommended to ensure the integrity and functioning of soil environment. Further studies are recommended to evaluate the long-term impact of Sb in the soil ecosystem through bioaccumulation and trophic transfer among soil-dwelling organisms.

Anti-aging Effect of Rutin in Caenorhabditis elegans and D-Gal-Induced Aging Mouse Model

Caenorhabditis elegans and D-Gal-induced aging mouse model were used to investigate the anti-aging effect of rutin. The effects of different concentrations of rutin (0, 12.5, 25, and 50 μg/mL) on locomotor behavior, reproductive rate, and lifespan of C. elegans were determined. For establishing the aging mouse model, D-Gal (200 mg/kg) was subcutaneously injected into the back of mice, and mice were treated with rutin (200 mg/kg). At the end of treatment, memory and motor function was assessed by nest building test, open field test, and Y-maze. Serum and brain tissue were collected from each mouse to examine the ROS, lipofuscin, MDA, GSH-Px, and SOD levels. The results showed that rutin prolonged the lifespan of C. elegans, and increased the number of eggs of C. elegans (p < 0.05). In addition, rutin significantly improved the exercise capacity in mice (p < 0.05) and significantly reduced brain tissue ROS (p < 0.05) and MDA (p < 0.01) levels. Meanwhile, rutin could enhance the activity of SOD (p < 0.05) and GSH-Px (p < 0.01) significantly in the serum and brain. In summary, rutin exhibits anti-senescence capabilities which could be ascribed to its antioxidant activities.

Comparative Analysis of Muscle Atrophy During Spaceflight, Nutritional Deficiency and Disuse in the Nematode Caenorhabditis elegans

While spaceflight is becoming more common than before, the hazards spaceflight and space microgravity pose to the human body remain relatively unexplored. Astronauts experience muscle atrophy after spaceflight, but the exact reasons for this and solutions are unknown. Here, we take advantage of the nematode C. elegans to understand the effects of space microgravity on worm body wall muscle. We found that space microgravity induces muscle atrophy in C. elegans from two independent spaceflight missions. As a comparison to spaceflight-induced muscle atrophy, we assessed the effects of acute nutritional deprivation and muscle disuse on C. elegans muscle cells. We found that these two factors also induce muscle atrophy in the nematode. Finally, we identified clp-4, which encodes a calpain protease that promotes muscle atrophy. Mutants of clp-4 suppress starvation-induced muscle atrophy. Such comparative analyses of different factors causing muscle atrophy in C. elegans could provide a way to identify novel genetic factors regulating space microgravity-induced muscle atrophy.

Increased mitochondrial Ca2+ contributes to health decline with age and Duchene muscular dystrophy in C. elegans

Sarcopenia is a geriatric syndrome characterized by an age-related decline in skeletal muscle mass and strength. Here, we show that suppression of mitochondrial calcium uniporter (MCU)-mediated Ca2+ influx into mitochondria in the body wall muscles of the nematode Caenorhabditis elegans improved the sarcopenic phenotypes, blunting movement and mitochondrial structural and functional decline with age. We found that normally aged muscle cells exhibited elevated resting mitochondrial Ca2+ levels and increased mitophagy to eliminate damaged mitochondria. Similar to aging muscle, we found that suppressing MCU function in muscular dystrophy improved movement via reducing elevated resting mitochondrial Ca2+ levels. Taken together, our results reveal that elevated resting mitochondrial Ca2+ levels contribute to muscle decline with age and muscular dystrophy. Further, modulation of MCU activity may act as a potential pharmacological target in various conditions involving muscle loss.

Evaluation of Human-Induced Pluripotent Stem Cells Derived from a Patient with Schwartz–Jampel Syndrome Revealed Distinct Hyperexcitability in the Skeletal Muscles

Schwartz–Jampel syndrome (SJS) is an autosomal recessive disorder caused by loss-of-function mutations in heparan sulfate proteoglycan 2 (HSPG2), which encodes the core basement membrane protein perlecan. Myotonia is a major criterion for the diagnosis of SJS; however, its evaluation is based solely on physical examination and can be challenging in neonates and young children. Furthermore, the pathomechanism underlying SJS-related myotonia is not fully understood, and effective treatments for SJS are limited. Here, we established a cellular model of SJS using patient-derived human-induced pluripotent stem cells. This model exhibited hyper-responsiveness to acetylcholine as a result of abnormalities in the perlecan molecule, which were confirmed via comparison of their calcium imaging with calcium imaging of satellite cells derived from Hspg2−/−-Tg mice, which exhibit myotonic symptoms similar to SJS symptoms. Therefore, our results confirm the utility of creating cellular models for investigating SJS and their application in evaluating myotonia in clinical cases, while also providing a useful tool for the future screening of SJS therapies.

ADAM10-a "multitasker" in sepsis: focus on its posttranslational target

BACKGROUND

Sepsis has a complex pathogenesis in which the uncontrolled systemic inflammatory response triggered by infection leads to vascular barrier disruption, microcirculation dysfunction and multiple organ dysfunction syndrome. Numerous recent studies reveal that a disintegrin and metalloproteinase 10 (ADAM10) acts as a "molecular scissor" playing a pivotal role in the inflammatory response during sepsis by regulating proteolysis by cleaving various membrane protein substrates, including proinflammatory cytokines, cadherins and Notch, which are involved in intercellular communication. ADAM10 can also act as the cellular receptor for Staphylococcus aureus α-toxin, leading to lethal sepsis. However, its substrate-specific modulation and precise targets in sepsis have not yet to be elucidated.

METHODS

We performed a computer-based online search using PubMed and Google Scholar for published articles concerning ADAM10 and sepsis.

CONCLUSIONS

In this review, we focus on the functions of ADAM10 in sepsis-related complex endothelium-immune cell interactions and microcirculation dysfunction through the diversity of its substrates and its enzymatic activity. In addition, we highlight the posttranslational mechanisms of ADAM10 at specific subcellular sites, or in multimolecular complexes, which will provide the insight to intervene in the pathophysiological process of sepsis caused by ADAM10 dysregulation.

Low-frequency electrical stimulation of bilateral hind legs by belt electrodes is effective for preventing denervation-induced atrophies in multiple skeletal muscle groups in rats

Belt electrode skeletal muscle electrical stimulation (B-SES) can simultaneously contract multiple muscle groups. Although the beneficial effects of B-SES in clinical situations have been elucidated, its molecular mechanism remains unknown. In this study, we developed a novel rodent B-SES ankle stimulation system to test whether low-frequency stimulation prevents denervation-induced muscle atrophy. Electrical stimulations (7‒8 Hz, 30 min) with ankle belt electrodes were applied to Sprague-Dawley rats daily for one week. All animals were assigned to the control (CONT), denervation-induced atrophy (DEN), and DEN + electrical stimulation (ES) groups. The tibialis anterior (TA) and gastrocnemius (GAS) muscles were used to examine the effect of ES treatment. After seven daily sessions of continuous stimulation, muscle wet weight (n = 8-11), and muscle fiber cross-sectional area (CSA, n = 4-6) of TA and GAS muscles were lower in DEN and DEN + ES than in CON. However, it was significantly higher in DEN than DEN + ES, showing that ES partially prevented muscle atrophy. PGC-1α, COX-IV, and citrate synthase activities (n = 6) were significantly higher in DEN + ES than in DEN. The mRNA levels of muscle proteolytic molecules, Atrogin-1 and Murf1, were significantly higher in DEN than in CONT, while B-SES significantly suppressed their expression (p < 0.05). In conclusion, low-frequency electrical stimulation of the bilateral ankles using belt electrodes (but not the pad electrodes) is effective in preventing denervation-induced atrophy in multiple muscles, which has not been observed with pad electrodes. Maintaining the mitochondrial quantity and enzyme activity by low-frequency electrical stimulation is key to suppressing muscle protein degradation.

Responses of bitter melon saponins to oxidative stress and aging via the IIS pathway linked with sir-2.1 and hlh-30

Saponins from bitter melon (BMS) exert potential bioactivities and pharmacological activities, including anti-oxidation and lifespan extension. However, the exact mechanisms of BMS in response to oxidative stress remain unknown. Results demonstrated that bitter melon saponins could strengthen locomotive activities (body bend and head thrashing) accompanied by delaying the muscle fiber damage with age in Caenorhabditis elegans. In addition, BMS inhibited the ROS accumulation, improved the activities of antioxidant enzymes like SOD (by 57.90% and 94.34% for 100 μg/ml and 200 μg/ml BMS, respectively) and CAT (by 51.45% and 56.91% for 100 μg/ml and 200 μg/ml BMS, respectively), and extend the lifespan of N2 and CL2006 worms under paraquat-induced oxidative stress. Mechanism study suggested that BMS modulated the mRNA expressions of oxidation-related regulators, like the upregulation of cat-1, hsf-1, sir-2.1, and hlh-30. Furthermore, gene-deficient mutants verified that IIS (insulin/insulin-like growth factor-1 signaling) pathway linked with sir-2.1 and hlh-30 factors were involved in the BMS's lifespan-extension effects under oxidative stress. In general, this study supplemented the explanation of BMS in promoting oxidation-resistance and lifespan-extension activities, which could be served as a potential candidate for anti-aging. PRACTICAL APPLICATIONS: Our previous studies have suggested that saponins from bitter melon exhibited fat-lowering activity in C. elegans. However, little was known about the mechanism underlying the anti-oxidation effects of BMS in C. elegans. Current results indicated that the IIS pathway linked with sir-2.1 and hlh-30 transcriptional factors jointly to increase the lifespan in BMS' responses to oxidative stress. Our findings are beneficial to understand the main nutritional ingredients in bitter melon, which are ideal and expected in functional foods for aging.

Bile Acids Induce Alterations in Mitochondrial Function in Skeletal Muscle Fibers

Cholestatic chronic liver disease is characterized by developing sarcopenia and elevated serum levels of bile acids. Sarcopenia is a skeletal muscle disorder with the hallmarks of muscle weakness, muscle mass loss, and muscle strength decline. Our previous report demonstrated that deoxycholic acid (DCA) and cholic acid (CA), through the membrane receptor TGR5, induce a sarcopenia-like phenotype in myotubes and muscle fibers. The present study aimed to evaluate the impact of DCA and CA on mitochondrial mass and function in muscle fibers and the role of the TGR5 receptor. To this end, muscle fibers obtained from wild-type and TGR5^−/− mice were incubated with DCA and CA. Our results indicated that DCA and CA decreased mitochondrial mass, DNA, and potential in a TGR5-dependent fashion. Furthermore, with TGR5 participation, DCA and CA also reduced the oxygen consumption rate and complexes I and II from the mitochondrial electron transport chain. In addition, DCA and CA generated more mitochondrial reactive oxygen species than the control, which were abolished in TGR5^−/− mice muscle fibers. Our results indicate that DCA and CA induce mitochondrial dysfunction in muscle fibers through a TGR5-dependent mechanism.

Mitochonic Acid 5 Improves Duchenne Muscular Dystrophy and Parkinson’s Disease Model of Caenorhabditis elegans

Mitochonic Acid 5 (MA-5) enhances mitochondrial ATP production, restores fibroblasts from mitochondrial disease patients and extends the lifespan of the disease model “Mitomouse”. Additionally, MA-5 interacts with mitofilin and modulates the mitochondrial inner membrane organizing system (MINOS) in mammalian cultured cells. Here, we used the nematode Caenorhabditis elegans to investigate whether MA-5 improves the Duchenne muscular dystrophy (DMD) model. Firstly, we confirmed the efficient penetration of MA-5 in the mitochondria of C. elegans. MA-5 also alleviated symptoms such as movement decline, muscular tone, mitochondrial fragmentation and Ca²⁺ accumulation of the DMD model. To assess the effect of MA-5 on mitochondria perturbation, we employed a low concentration of rotenone with or without MA-5. MA-5 significantly suppressed rotenone-induced mitochondria reactive oxygen species (ROS) increase, mitochondrial network fragmentation and nuclear destruction in body wall muscles as well as endogenous ATP levels decline. In addition, MA-5 suppressed rotenone-induced degeneration of dopaminergic cephalic (CEP) neurons seen in the Parkinson’s disease (PD) model. Furthermore, the application of MA-5 reduced mitochondrial swelling due to the immt-1 null mutation. These results indicate that MA-5 has broad mitochondrial homing and MINOS stabilizing activity in metazoans and may be a therapeutic agent for these by ameliorating mitochondrial dysfunction in DMD and PD.

Orai1-STIM1 Regulates Increased Ca2+ Mobilization, Leading to Contractile Duchenne Muscular Dystrophy Phenotypes in Patient-Derived Induced Pluripotent Stem Cells

Ca²⁺ overload is one of the factors leading to Duchenne muscular dystrophy (DMD) pathogenesis. However, the molecular targets of dystrophin deficiency-dependent Ca²⁺ overload and the correlation between Ca²⁺ overload and contractile DMD phenotypes in in vitro human models remain largely elusive. In this study, we utilized DMD patient-derived induced pluripotent stem cells (iPSCs) to differentiate myotubes using doxycycline-inducible MyoD overexpression, and searched for a target molecule that mediates dystrophin deficiency-dependent Ca²⁺ overload using commercially available chemicals and siRNAs. We found that several store-operated Ca²⁺ channel (SOC) inhibitors effectively prevented Ca²⁺ overload and identified that STIM1–Orai1 is a molecular target of SOCs. These findings were further confirmed by demonstrating that STIM1–Orai1 inhibitors, CM4620, AnCoA4, and GSK797A, prevented Ca²⁺ overload in dystrophic myotubes. Finally, we evaluated CM4620, AnCoA4, and GSK7975A activities using a previously reported model recapitulating a muscle fatigue-like decline in contractile performance in DMD. All three chemicals ameliorated the decline in contractile performance, indicating that modulating STIM1–Orai1-mediated Ca²⁺ overload is effective in rescuing contractile phenotypes. In conclusion, SOCs are major contributors to dystrophin deficiency-dependent Ca²⁺ overload through STIM1–Orai1 as molecular mediators. Modulating STIM1–Orai1 activity was effective in ameliorating the decline in contractile performance in DMD.

Morphological Changes in the Myotendinous Junction of mdx Mice

The myotendinous junction (MTJ) is the interface between muscle and tendon, and it is the main area of force transmission of the locomotor apparatus. Dystrophic processes promote pathological injury which affects the skeletal muscle and can influence the morphology of the MTJ. This study aimed to investigate the adaptations in MTJ morphology of mdx mice in the tibialis anterior muscle. Male mice (n = 24) were divided into Control—C57bl/10 and mdx—C57bl/10mdx (Duchenne muscular dystrophy experimental model). In the mdx group, centralized nuclei with a large area and greater deposition of type III collagen (fibrosis) were observed. Also, shorter sarcomeres and sarcoplasmatic projections of MTJ were observed. We concluded that the adaptations in mdx mice demonstrated extensive impairment in the MTJ region with reduced ultrastructures.

Vitamin Intake and Loss of Muscle Mass in Older People with Type 2 Diabetes: A Prospective Study of the KAMOGAWA-DM Cohort

The aim of this prospective cohort study was to examine the relationships between the intakes of various vitamins and the loss of muscle mass in older people with type 2 diabetes (T2DM). The change in skeletal muscle mass index (SMI, kg/m²) (kg/m²/year) was defined as follows: (SMI at baseline (kg/m²) - SMI at follow-up (kg/m²))/follow-up period (year). The rate of SMI reduction (%) was calculated as follows (the change in SMI (kg/m²/year)/SMI at baseline (kg/m²)) × 100. The rate of SMI reduction ≥ 1.2% was considered as the loss of muscle mass. Among 197 people with T2DM, 47.2% of them experienced the loss of muscle mass at the 13.7 ± 5.2 month follow-up. Vitamin B1 (0.8 ± 0.3 vs. 0.8 ± 0.3 mg/day, p = 0.031), vitamin B12 (11.2 ± 8.3 vs. 13.4 ± 7.5 μg/day, p = 0.049), and vitamin D (16.5 ± 12.2 vs. 21.6 ± 13.0 μg/day, p = 0.004) intakes in people with the loss of muscle mass were significantly lower than those without. Vitamin D intake was related to the loss of muscle mass after adjusting for sex, age, exercise, alcohol, smoking, body mass index, SMI, glucagon-like peptide-1 agonist, sodium glucose cotransporter-2 inhibitor, insulin, HbA1c, creatinine, energy intake, and protein intake (adjusted odds ratio 0.93, 95% confidence interval: 0.88-0.97, p = 0.003). This study showed that vitamin D intake was related to the loss of muscle mass in older people with T2DM. Vitamin B12 intake tended to be related to the loss of muscle mass, although vitamin A, vitamin B2, vitamin B6, vitamin C, and vitamin E intake were not related.

Caenorhabditis elegans as a Model System for Duchenne Muscular Dystrophy

The nematode worm Caenorhabditis elegans has been used extensively to enhance our understanding of the human neuromuscular disorder Duchenne Muscular Dystrophy (DMD). With new arising clinically relevant models, technologies and treatments, there is a need to reconcile the literature and collate the key findings associated with this model.

Abnormal Calcium Handling in Duchenne Muscular Dystrophy: Mechanisms and Potential Therapies

Duchenne muscular dystrophy (DMD) is an X-linked muscle-wasting disease caused by the loss of dystrophin. DMD is associated with muscle degeneration, necrosis, inflammation, fatty replacement, and fibrosis, resulting in muscle weakness, respiratory and cardiac failure, and premature death. There is no curative treatment. Investigations on disease-causing mechanisms offer an opportunity to identify new therapeutic targets to treat DMD. An abnormal elevation of the intracellular calcium (Cai2+) concentration in the dystrophin-deficient muscle is a major secondary event, which contributes to disease progression in DMD. Emerging studies have suggested that targeting Ca²⁺-handling proteins and/or mechanisms could be a promising therapeutic strategy for DMD. Here, we provide an updated overview of the mechanistic roles the sarcolemma, sarcoplasmic/endoplasmic reticulum, and mitochondria play in the abnormal and sustained elevation of Cai2+ levels and their involvement in DMD pathogenesis. We also discuss current approaches aimed at restoring Ca²⁺ homeostasis as potential therapies for DMD.

Mitochondrial hydrogen sulfide supplementation improves health in the C. elegans Duchenne muscular dystrophy model

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder characterized by progressive muscle degeneration and weakness due to mutations in the dystrophin gene. The symptoms of DMD share similarities with those of accelerated aging. Recently, hydrogen sulfide (H2S) supplementation has been suggested to modulate the effects of age-related decline in muscle function, and metabolic H2S deficiencies have been implicated in affecting muscle mass in conditions such as phenylketonuria. We therefore evaluated the use of sodium GYY4137 (NaGYY), a H2S-releasing molecule, as a possible approach for DMD treatment. Using the dys-1(eg33) Caenorhabditis elegans DMD model, we found that NaGYY treatment (100 µM) improved movement, strength, gait, and muscle mitochondrial structure, similar to the gold-standard therapeutic treatment, prednisone (370 µM). The health improvements of either treatment required the action of the kinase JNK-1, the transcription factor SKN-1, and the NAD-dependent deacetylase SIR-2.1. The transcription factor DAF-16 was required for the health benefits of NaGYY treatment, but not prednisone treatment. AP39 (100 pM), a mitochondria-targeted H2S compound, also improved movement and strength in the dys-1(eg33) model, further implying that these improvements are mitochondria-based. Additionally, we found a decline in total sulfide and H2S-producing enzymes in dystrophin/utrophin knockout mice. Overall, our results suggest that H2S deficit may contribute to DMD pathology, and rectifying/overcoming the deficit with H2S delivery compounds has potential as a therapeutic approach to DMD treatment.

Worsening renal function during hospitalization in elderly patients with heart failure: an independent factor of activities of daily living decline

This study aimed to clarify the effects of worsening renal function (WRF) during hospitalization on activities of daily living (ADL) at discharge of elderly heart failure (HF) patients. We included 323 consecutive patients hospitalized for HF who were prescribed phase I cardiac rehabilitation (CR) from November 2017 to April 2019. WRF was defined as a relative increase from baseline in serum creatinine of 25% or that in serum creatinine ≥ 0.3 mg/dL during hospitalization. The indices of ADL and physical function were the functional independence measure (FIM), short physical performance battery (SPPB) and 10-m comfortable gait speed as assessed at discharge. We compared background factors, clinical parameters, walking level before hospitalization, physical function, and FIM in two groups. Multiple regression analysis was performed with FIM at discharge as the dependent variable and items with P < 0.05 in bivariate correlation as independent variables. Ultimately, 160 patients were included and divided into the WRF group (n = 72) and non-WRF group (n = 88). FIM, SPPB, and 10-m comfortable walking speed were significantly lower in the WRF group. Moreover, even after adjustment for confounding factors (age, Hb, eGFR, CKD, GNRI, start day of standing), eGFR on admission (β = 0.12), WRF (β =  - 6.42) and walking level before hospitalization (β = - 10.00) were independent factors of ADL decline at discharge (adjusted R² = 0.46). WRF during hospitalization of elderly HF patients was a factor affecting ADL decline at discharge along with walking level before hospitalization and renal function at admission.

Epoxyeicosatrienoic acids inhibit the activation of NLRP3 inflammasome in murine macrophages

Epoxyeicosatrienoic acids (EETs) derived from arachidonic acid exert anti-inflammation effects. We have reported that blocking the degradation of EETs with a soluble epoxide hydrolase (sEH) inhibitor protects mice from lipopolysaccharide (LPS)-induced acute lung injury (ALI). The underlying mechanisms remain essential questions. In this study, we investigated the effects of EETs on the activation of nucleotide-binding domain leucine-rich repeat-containing receptor, pyrin domain-containing-3 (NLRP3) inflammasome in murine macrophages. In an LPS-induced ALI murine model, we found that sEH inhibitor 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl), TPPU, profoundly attenuated the pathological injury and inhibited the activation of the NLRP3 inflammasome, characterized by the reduction of the protein expression of NLRP3, ASC, pro-caspase-1, interleukin precursor (pro-IL-1β), and IL-1β p17 in the lungs of LPS-treated mice. In vitro, primary peritoneal macrophages from C57BL/6 were primed with LPS and activated with exogenous adenosine triphosphate (ATP). TPPU treatment remarkably reduced the expression of NLRP3 inflammasome-related molecules and blocked the activation of NLRP3 inflammasome. Importantly, four EETs (5,6-EET, 8,9-EET, 11,12-EET, and 14,15-EET) inhibited the activation of NLRP3 inflammasome induced by LPS + ATP or LPS + nigericin in macrophages in various degree. While the inhibitory effect of 5,6-EET was the weakest. Mechanismly, EETs profoundly decreased the content of reactive oxygen species (ROS) and restored the calcium overload in macrophages receiving LPS + ATP stimulation. In conclusion, this study suggests that EETs inhibit the activation of the NLRP3 inflammasome by suppressing calcium overload and ROS production in macrophages, contributing to the therapeutic potency to ALI.

Space Radiation Biology for "Living in Space"

Space travel has advanced significantly over the last six decades with astronauts spending up to 6 months at the International Space Station. Nonetheless, the living environment while in outer space is extremely challenging to astronauts. In particular, exposure to space radiation represents a serious potential long-term threat to the health of astronauts because the amount of radiation exposure accumulates during their time in space. Therefore, health risks associated with exposure to space radiation are an important topic in space travel, and characterizing space radiation in detail is essential for improving the safety of space missions. In the first part of this review, we provide an overview of the space radiation environment and briefly present current and future endeavors that monitor different space radiation environments. We then present research evaluating adverse biological effects caused by exposure to various space radiation environments and how these can be reduced. We especially consider the deleterious effects on cellular DNA and how cells activate DNA repair mechanisms. The latest technologies being developed, e.g., a fluorescent ubiquitination-based cell cycle indicator, to measure real-time cell cycle progression and DNA damage caused by exposure to ultraviolet radiation are presented. Progress in examining the combined effects of microgravity and radiation to animals and plants are summarized, and our current understanding of the relationship between psychological stress and radiation is presented. Finally, we provide details about protective agents and the study of organisms that are highly resistant to radiation and how their biological mechanisms may aid developing novel technologies that alleviate biological damage caused by radiation. Future research that furthers our understanding of the effects of space radiation on human health will facilitate risk-mitigating strategies to enable long-term space and planetary exploration.