Inhibition of DRP1-dependent mitochondrial fission by Mdivi-1 alleviates atherosclerosis through the modulation of M1 polarization

Quiles J.M., Gustafsson Å.B.

Mitochondria are organelles involved in the regulation of various important cellular processes, ranging from ATP generation to immune activation. A healthy mitochondrial network is essential for cardiovascular function and adaptation to pathological stressors. Mitochondria undergo fission or fusion in response to various environmental cues, and these dynamic changes are vital for mitochondrial function and health. In particular, mitochondrial fission is closely coordinated with the cell cycle and is linked to changes in mitochondrial respiration and membrane permeability. Another key function of fission is the segregation of damaged mitochondrial components for degradation by mitochondrial autophagy (mitophagy). Mitochondrial fission is induced by the large GTPase dynamin-related protein 1 (DRP1) and is subject to sophisticated regulation. Activation requires various post-translational modifications of DRP1, actin polymerization and the involvement of other organelles such as the endoplasmic reticulum, Golgi apparatus and lysosomes. A decrease in mitochondrial fusion can also shift the balance towards mitochondrial fission. Although mitochondrial fission is necessary for cellular homeostasis, this process is often aberrantly activated in cardiovascular disease. Indeed, strong evidence exists that abnormal mitochondrial fission directly contributes to disease development. In this Review, we compare the physiological and pathophysiological roles of mitochondrial fission and discuss the therapeutic potential of preventing excessive mitochondrial fission in the heart and vasculature. In this Review, Quiles and Gustafsson compare the physiological and pathophysiological roles of mitochondrial fission and discuss the therapeutic potential of preventing excessive mitochondrial fission in the heart and vasculature.

Wisitpongpun P., Potup P., Usuwanthim K.

Macrophages are a type of innate immune cell that activates the NLRP3 inflammasome, causing the release of the cytokine IL-1β, which is a crucial mediator of the inflammatory response. NLRP3 activation that is dysregulated worsens a variety of inflammatory and autoimmune diseases, as well as neurodegenerative diseases. Oleamide is an endogenous fatty acid amide that was first determined as a sleep-inducing molecule and later shown to have wide-ranging beneficial effects on the central nervous system. How oleamide influences human macrophage polarization and NLRP3-inflammasome activation remains unclear. The effect of oleamide on macrophage polarization was explored using an in vitro culture of primary human monocyte-derived macrophages (MDMs) supplemented with human serum-containing media. Cellular and molecular mechanisms of oleamide-regulated MDMs polarization were also investigated. Results showed that oleamide promoted naïve macrophages (M0) toward the M1 phenotype by upregulating M1-associated genes (IL-1β, iNOS, CXCL10), along with downregulation of M2-associated genes (Arg-1, CD206, CCL22). Cell surface expression indicated that oleamide enhanced CD80 expression in M0 naïve macrophages and hider CD206 and CD163 expression in M2 macrophages. Higher production of IL-1β cytokine was observed but with no alteration in IL-6 and TNF-α levels by MDMs and differentiated THP-1 models. Whether oleamide functioned as a second signal that activated the NLRP3 inflammasome and mediated IL-1β production was further investigated using LPS-primed MDMs followed by oleamide treatment that induced activation of inflammasome-related proteins including NLRP3, ASC, cleaved casp-1, and cleaved IL-1β. These findings suggested that oleamide promoted M1 macrophage polarization and increased IL-1β production by activating the NLRP3 inflammasome in primary MDMs. This research reveals a new function for oleamide as well as prospective targets for treating NLRP3-related inflammatory disorders.

Lu J., Xie S., Deng Y., Xie X., Liu Y.

Activated innate immune cells infiltrating the valve and their secreted cytokines drive the differentiation of valve interstitial cells into myofibroblastic and osteoblastic phenotypes in calcified aortic valve stenosis (CAVS). In this study, we investigated how NLRP3 inhibition with CY-09 reduces aortic valve stenosis and calcification.ApoE-/- mice were fed a high-fat diet for 24 weeks with or without intraperitoneal injection of 2.5 mg/kg/day NLRP3 inhibitor CY-09 for 42 consecutive days, while the control group mice were fed a normal diet. The valve function was monitored by echocardiography; calcified nodules were assessed by Von Kossa staining; and calcification-related molecules, inflammatory factors, and white leucocyte influx into the valve were assessed by immunohistochemistry, TUNEL assay, and PCR.Mice treated with CY-09 exhibited improved aortic valve function and reduced valve calcification deposition. CY-09 intervention significantly downregulated the elevated expression of the NLRP3 inflammasome pathway molecules NLRP3, caspase-1, and IL-1β and the osteogenic calcification markers RUNX2, SPARC, and BMP2 in stenotic valves, while the number of apoptotic cells and dystrophic calcification markers CDH11 and α- SMA did not change significantly. Inhibition of NLRP3 activity also reduced the ratio of M1/M2 macrophages, prevented the shift of macrophages towards the M1 phenotype, and downregulated the levels of the proinflammatory factors IL-6 and TNF-α.This study provides a proof-of-concept that pharmacological inhibition of the NLRP3 inflammasome is a feasible strategy for alleviating aortic valve calcification and stenosis.

Ding J., Zhang Z., Li S., Wang W., Du T., Fang Q., Wang Y., Wang D.W.

Mitochondrial division inhibitor 1(Mdivi-1) has been shown to play a beneficial role in a variety of diseases, mainly by inhibiting Drp1-mediated mitochondrial fission. The effects of Mdivi-1 on cardiac fibrosis at infarcted border zone area and its possible mechanism remain unclear. This study aimed to investigate the effects of Mdivi-1 on reactive cardiac fibrosis and cardiac function post myocardial infarction and its potential mechanisms. Mice were randomly divided into six groups (n = 9 for each group): Sham; Mdivi-1; MI 7d; MI 14d; MI 28d; MI 28d + Mdivi-1. The MI model was induced by ligation of LAD coronary artery. Mdivi-1 (1 mg/kg) was administered to mice every other day at a time from the second day until the sacrifice of the mice (total 14 injection of Mdivi-1). In vitro experiments, the effect of Mdivi-1 on TGF-β1-induced fibrosis-related pathophysiological changes of fibroblasts was examined in NIH3T3 cells. We found that Mdivi-1 significantly attenuated fibroblast activation, collagen production and fibrosis at infarcted border zone after MI, improved impaired heart function. Mechanistically, we observed that Mdivi-1 reduced the protein expression of P-Drp1-S616 and abnormal mitochondrial fission of cardiac fibroblasts in the infarcted border zone area. In addition, we found that the effects of Mdivi-1 partially relied on increasing the expression of Hmox1 and inhibiting oxidative stress. In conclusion, Mdivi-1 could attenuate cardiac fibrosis at infarcted border zone and improve impaired heart function partially through attenuation of Drp1-mediated mitochondrial fission. Moreover, inhibition of oxidative stress, which is possible due to the up-regulation of Hmox1, may be another potential mechanism of action of Mdivi-1.

Wang S., Yang S., Chen Y., Chen Y., Li R., Han S., Kamili A., Wu Y., Zhang W.

Introduction: Atherosclerosis is a chronic disease characterized by the inflammatory process and lipid depositions. We previously reported that microRNA-216a (miR-216a) can accelerate the progression of atherosclerosis by promoting the polarization of M1 pro-inflammatory phenotype. Ginsenoside Rb2 (Rb2), the major pharmacologically active compound extracted from ginseng, has a high affinity to miR-216a. In this study, we aimed to investigate whether Rb2 can counteract the effect of miR-216a in macrophages to ameliorate atherosclerosis.Methods: The apolipoprotein E deficiency (ApoE−/−) mice model was chronically infected with miR-216a adenovirus via the tail vein and then intraperitoneally injected with Rb2. The plaque lesion area and stability of thoracic aorta were examined. The human myeloid leukemia mononuclear cells (THP-1) or human peripheral blood mononuclear cells (PBMCs) were cultured in vitro, transfected with miR-216a mimics, and treated with Rb2 to explore the mechanisms of Rb2 on the polarization of M1 macrophages, inflammatory process, and lipid accumulation.Results: In the atherosclerotic ApoE−/− mice model, miR-216a greatly increased en face aortic lesion area of the thoracic aorta, lipid accumulation, and M1 macrophages infiltration in plaques, whereas these effects of miR-216a on atherosclerosis burden were significantly alleviated by Rb2 treatment. In the in vitro THP-1 model, the flow cytometry experiment showed that Rb2 treatment inhibited miR-216a–mediated polarization of M1 macrophages characterized by the surface marker CD86 expression but had no effects on M2 polarization characterized by the surface marker CD206 expression. Mechanistically, Rb2 suppressed the miR-216a–mediated inflammatory response through the Smad3/nuclear factor kappa B inhibitor alpha pathway. Moreover, Rb2 reduced the lipid uptake and promoted cholesterol efflux by counteracting the effects of miR-216a in the THP-1–derived foam cells and in the PBMC-derived foam cells under the oxidized low-density lipoproteins.Conclusion: Our findings indicated that Rb2 might be a potential therapeutic molecule for atherosclerosis by attenuating the atherosclerosis plaque lesion, lipid accumulation, and M1 macrophages polarization by targeting miR-216a. Given that accumulation of foam cells in the intima takes place chronically, the role of Rb2 in atherosclerosis progression needs further investigation.

Jiang C., Xie S., Yang G., Wang N.

Inflammation is an intricate biological response of body tissues to detrimental stimuli. Cardiovascular disease (CVD) is the leading cause of death worldwide, and inflammation is well documented to play a role in the development of CVD, especially atherosclerosis (AS). Emerging evidence suggests that activation of the NOD-like receptor (NLR) family and the pyridine-containing domain 3 (NLRP3) inflammasome is instrumental in inflammation and may result in AS. The NLRP3 inflammasome acts as a molecular platform that triggers the activation of caspase-1 and the cleavage of pro-interleukin (IL)-1β, pro-IL-18, and gasdermin D (GSDMD). The cleaved GSDMD forms pores in the cell membrane and initiates pyroptosis, inducing cell death and the discharge of intracellular pro-inflammatory factors. Hence, the NLRP3 inflammasome is a promising target for anti-inflammatory therapy against AS. In this review, we systematically summarized the current understanding of the activation mechanism of NLRP3 inflammasome, and the pathological changes in AS involving NLRP3. We also discussed potential therapeutic strategies targeting NLRP3 inflammasome to combat AS.

Chen W., Schilperoort M., Cao Y., Shi J., Tabas I., Tao W.

Nanotechnology could improve our understanding of the pathophysiology of atherosclerosis and contribute to the development of novel diagnostic and therapeutic strategies to further reduce the risk of cardiovascular disease. Macrophages have key roles in atherosclerosis progression and, therefore, macrophage-associated pathological processes are important targets for both diagnostic imaging and novel therapies for atherosclerosis. In this Review, we highlight efforts in the past two decades to develop imaging techniques and to therapeutically manipulate macrophages in atherosclerotic plaques with the use of rationally designed nanoparticles. We review the latest progress in nanoparticle-based imaging modalities that can specifically target macrophages. Using novel molecular imaging technology, these modalities enable the identification of advanced atherosclerotic plaques and the assessment of the therapeutic efficacy of medical interventions. Additionally, we provide novel perspectives on how macrophage-targeting nanoparticles can deliver a broad range of therapeutic payloads to atherosclerotic lesions. These nanoparticles can suppress pro-atherogenic macrophage processes, leading to improved resolution of inflammation and stabilization of plaques. Finally, we propose future opportunities for novel diagnostic and therapeutic strategies and provide solutions to challenges in this area for the purpose of accelerating the clinical translation of nanomedicine for the treatment of atherosclerotic vascular disease. In this Review, Tao and colleagues discuss the latest advances in nanoparticle-based imaging and therapeutic approaches targeting macrophages in atherosclerotic plaques, highlight opportunities for novel macrophage-targeting nanomedicines for atherosclerosis diagnosis and treatment, and provide solutions to challenges in this area to accelerate clinical translation.

Jiao Y., Zhang T., Zhang C., Ji H., Tong X., Xia R., Wang W., Ma Z., Shi X.

Polymorphonuclear neutrophils (PMNs) play an important role in sepsis-related acute lung injury (ALI). Accumulating evidence suggests PMN-derived exosomes as a new subcellular entity acting as a fundamental link between PMN-driven inflammation and tissue damage. However, the role of PMN-derived exosomes in sepsis-related ALI and the underlying mechanisms remains unclear. Tumor necrosis factor-α (TNF-α), a key regulator of innate immunity in sepsis-related ALI, was used to stimulate PMNs from healthy C57BL/6J mice in vitro. Exosomes isolated from the supernatant were injected to C57BL/6J wild-type mice intraperitoneally (i.p.) and then examined for lung inflammation, macrophage (Mϕ) polarization and pyroptosis. In vitro co-culture system was applied where the mouse Raw264.7 macrophages or bone marrow-derived macrophages (BMDMs) were co-cultured with PMN-derived exosomes to further confirm the results of in vivo animal study and explore the potential mechanisms involved. Exosomes released by TNF-α-stimulated PMNs (TNF-Exo) promoted M1 macrophage activation after in vivo i.p. injection or in vitro co-culture. In addition, TNF-Exo primed macrophage for pyroptosis by upregulating NOD-like receptor 3 (NLRP3) inflammasome expression through nuclear factor κB (NF-κB) signaling pathway. Mechanistic studies demonstrated that miR-30d-5p mediated the function of TNF-Exo by targeting suppressor of cytokine signaling (SOCS-1) and sirtuin 1 (SIRT1) in macrophages. Furthermore, intravenous administration of miR-30d-5p inhibitors significantly decreased TNF-Exo or cecal ligation and puncture (CLP)-induced M1 macrophage activation and macrophage death in the lung, as well as the histological lesions. The present study demonstrated that exosomal miR-30d-5p from PMNs contributed to sepsis-related ALI by inducing M1 macrophage polarization and priming macrophage pyroptosis through activating NF-κB signaling. These findings suggest a novel mechanism of PMN-Mϕ interaction in sepsis-related ALI, which may provide new therapeutic strategies in sepsis patients.

Zeng W., Wu D., Sun Y., Suo Y., Yu Q., Zeng M., Gao Q., Yu B., Jiang X., Wang Y.

NLRP3 inflammasome is a vital player in macrophages pyroptosis, which is a type of proinflammatory cell-death and takes part in the pathogenesis of atherosclerosis. In this study, we used apoE−/− mice and ox-LDL induced THP-1 derived macrophages to explore the mechanisms of MCC950, a selective NLRP3 inhibitor in treating atherosclerosis. For the in vivo study, MCC950 was intraperitoneal injected to 8-week-old apoE−/− mice fed with high-fat diet for 12 weeks. For the in vitro study, THP-1 derived macrophages were treated with ox-LDL and MCC950 for 48 h. MCC950 administration reduced plaque areas and macrophages contents, but did not improve the serum lipid profiles in aortic root of apoE−/− mice. MCC950 inhibited the activation of NLRP3/ASC/Caspase-1/GSDMD-N axis, and alleviated macrophages pyroptosis and the production of IL-1β and IL-18 both in aorta and in cell lysates. However, MCC950 did not affect the expression of TLR4 or the mRNA levels of NLRP3 inflammasome and its downstream proteins, suggesting that MCC950 had no effects on the priming of NLRP3 inflammasome activation in macrophages. The anti-atherosclerotic mechanisms of MCC950 on attenuating macrophages inflammation and pyroptosis involved in inhibiting the assembly and activation of NLRP3 inflammasome, rather than interrupting its priming.

Xu T., Dong Q., Luo Y., Liu Y., Gao L., Pan Y., Zhang D.

Porphyromonas gingivalis (P. gingivalis), a key pathogen in periodontitis, has been shown to accelerate the progression of atherosclerosis (AS). However, the definite mechanisms remain elusive. Emerging evidence supports an association between mitochondrial dysfunction and AS. In our study, the impact of P. gingivalis on mitochondrial dysfunction and the potential mechanism were investigated. The mitochondrial morphology of EA.hy926 cells infected with P. gingivalis was assessed by transmission electron microscopy, mitochondrial staining, and quantitative analysis of the mitochondrial network. Fluorescence staining and flow cytometry analysis were performed to determine mitochondrial reactive oxygen species (mtROS) and mitochondrial membrane potential (MMP) levels. Cellular ATP production was examined by a luminescence assay kit. The expression of key fusion and fission proteins was evaluated by western blot and immunofluorescence. Mdivi-1, a specific Drp1 inhibitor, was used to elucidate the role of Drp1 in mitochondrial dysfunction. Our findings showed that P. gingivalis infection induced mitochondrial fragmentation, increased the mtROS levels, and decreased the MMP and ATP concentration in vascular endothelial cells. We observed upregulation of Drp1 (Ser616) phosphorylation and translocation of Drp1 to mitochondria. Mdivi-1 blocked the mitochondrial fragmentation and dysfunction induced by P. gingivalis. Collectively, these results revealed that P. gingivalis infection promoted mitochondrial fragmentation and dysfunction, which was dependent on Drp1. Mitochondrial dysfunction may represent the mechanism by which P. gingivalis exacerbates atherosclerotic lesions.

Cai Y., Wen J., Ma S., Mai Z., Zhan Q., Wang Y., Zhang Y., Chen H., Li H., Wu W., Li R., Luo C.

Macrophage polarization plays a vital impact in triggering atherosclerosis (AS) progression and regression. Huang-Lian-Jie-Du Decoction (HLJDD), a famous traditional Chinese decoction, displays notable anti-inflammatory and lipid-lowering effects in different animal models. However, its effects and mechanisms on AS have not been clearly defined. We determined whether HLJDD attenuated atherosclerosis and plaques vulnerability by regulating macrophage polarization in ApoE−/− mice induced by high-fat diet (HFD). Furthermore, we investigated the effects of HLJDD on macrophage polarization in oxidized low-density lipoprotein (ox-LDL) induced RAW264.7 cells. For in vivo assay, compared with the model group, HLJDD ameliorated lipid metabolism, with significantly decreased levels of serum triglyceride, total cholesterol (CHOL), and lipid density lipoprotein. HLJDD suppressed serum tumor necrosis factor α (TNF-α) and IL-1β levels with increased serum IL-10 level, and inhibited mRNA level of NLRP3 inflammasome in carotid tissues. HLJDD enhanced carotid lesion stability by decreasing macrophage infiltration together with increased expression of collagen fibers and α-SMA. Moreover, HLJDD inhibited M1 macrophage polarization, which decreased the expression and mRNA levels of M1 markers [inducible nitric oxide synthase (iNOS) and CD86]. HLJDD enhanced alternatively activated macrophage (M2) activation, which increased the expression and mRNA levels of M2 markers (Arg-1 and CD163). For in vitro assay, HLJDD inhibited foam cell formation in RAW264.7 macrophages disturbed by ox-LDL. Besides, groups with ox-LDL plus HLJDD drug had a lower expression of CD86 and mRNA levels of iNOS, CD86, and IL-1β, but higher expression of CD163 and mRNA levels of Arg-1, CD163, and IL-10 than ox-LDL group. Collectively, our results revealed that HLJDD alleviated atherosclerosis and promoted plaque stability by suppressing M1 polarization and enhancing M2 polarization.

Roy P., Orecchioni M., Ley K.

Atherosclerosis is the root cause of many cardiovascular diseases. Extensive research in preclinical models and emerging evidence in humans have established the crucial roles of the innate and adaptive immune systems in driving atherosclerosis-associated chronic inflammation in arterial blood vessels. New techniques have highlighted the enormous heterogeneity of leukocyte subsets in the arterial wall that have pro-inflammatory or regulatory roles in atherogenesis. Understanding the homing and activation pathways of these immune cells, their disease-associated dynamics and their regulation by microbial and metabolic factors will be crucial for the development of clinical interventions for atherosclerosis, including potentially vaccination-based therapeutic strategies. Here, we review key molecular mechanisms of immune cell activation implicated in modulating atherogenesis and provide an update on the contributions of innate and adaptive immune cell subsets in atherosclerosis. Atherosclerosis involves a maladaptive inflammatory response. This Review summarizes the contributions of key innate and adaptive immune cell subsets and describes diverse mechanisms that regulate their activation. It also discusses the feasibility of developing immune-targeted interventions, such as tolerogenic vaccines.

Deng Y., Li S., Chen Z., Wang W., Geng B., Cai J.

Vascular smooth muscle cell (VSMC) phenotypic switch plays an essential role in the pathogenesis of hypertension. Mitochondrial dynamics, such as mitochondrial fission, can also contribute to VSMC phenotypic switch. Whether mitochondrial fission act as a novel target for anti-hypertensive drug development remains unknown. In the present study, we confirmed that angiotensin II (AngII) rapidly and continuously induced mitochondrial fission in VSMCs. We also detected the phosphorylation status of dynamin-related protein-1 (Drp1), a key protein involved in mitochondrial fission, at Ser616 site; and observed Drp1 mitochondrial translocation in VSMCs or arteries of AngII-induced hypertensive mice. The Drp1 inhibitor mitochondrial division inhibitor-1 (Mdivi-1) dramatically reversed AngII-induced Drp1 phosphorylation, mitochondrial fission, and reactive oxidative species generation. Treatment with Mdivi-1 (20 mg/kg/every other day) significantly attenuated AngII-induced hypertension (22 mmHg), arterial remodeling, and cardiac hypertrophy, in part by preventing VSMC phenotypic switch. In addition, Mdivi-1 treatment was not associated with liver or renal functional injury. Collectively, these results indicate that Mdivi-1 inhibited mitochondrial fission, recovered mitochondrial activity, and prevented AngII-induced VSMC phenotypic switch, resulting in reduced hypertension. • Mitochondria fission is an integrated part in AngII-triggered VSMCs phenotypic switch. • AngII promotes Drp1 phosphorylation at Ser616, and Drp1 mitochondrial translocation. • Mdivi-1 supplementation inhibited AngII-induced VSMCs phenotypic switch, then attenuation hypertension.

Li L., Mu Z., Liu P., Wang Y., Yang F., Han X.

Atopic dermatitis (AD) is a chronic inflammatory cutaneous disorder with few treatment options. Dynamin-related protein 1 (Drp1)-dependent mitochondrial fission contributes to the activation of NLRP3 inflammasome, and inhibiting Drp1 has been become an attractive therapeutic strategy for inflammatory diseases. This study aimed to investigate the effects of Drp1 inhibitor mdivi-1 on experimental AD. We firstly detected the effects of mdivi-1 on primary human keratinocytes in an inflammatory cocktail-induced AD-related inflammation in vitro. Results showed that mdivi-1 inhibited NLRP3 inflammasome activation and pyroptosis which were evidenced by decreased expression of NLRP3, ASC, cleavage of caspase-1, GSDMD-NT, mature interleukin (IL)-1β and IL-18 in keratinocytes under AD-like inflammation. Next, mouse model of AD-like skin lesions was induced by epicutaneous application of 2,4-dinitrochlorobenzene (DNCB) and mdivi-1 (25 mg/kg/day, days 5-33 during construction of AD model) was intraperitoneally injected into DNCB-induced mice. AD mice with mdivi-1 treatment exhibited ameliorated AD symptoms, lower serum IgE level, and reduced epidermal thickening, mast cells infiltration, and production of IL-4, IL-5 and IL-13 in the lesional tissues. Indeed, mdivi-1 significantly inhibited NLRP3 inflammasome activation and pyroptotic injury occurred in DNCB-treated skin tissues. Mechanically, mdivi-1 regulated the expression of mitochondrial dynamic proteins and suppressed the activation of NF-κB signal pathway which is an upstream of NLRP3 inflammasome both in vitro and in vivo. This study demonstrated that mdivi-1 could protect against experimental AD through inhibiting the activation of NLRP3 inflammasome and subsequent inflammatory cytokine release, and mdivi-1 might exert this function by inhibiting mitochondrial fission and subsequently blocking NF-κB pathway.

Kyriakoudi S., Drousiotou A., Petrou P.P.

Mitochondria are dynamic organelles, the morphology of which is tightly linked to their functions. The interplay between the coordinated events of fusion and fission that are collectively described as mitochondrial dynamics regulates mitochondrial morphology and adjusts mitochondrial function. Over the last few years, accruing evidence established a connection between dysregulated mitochondrial dynamics and disease development and progression. Defects in key components of the machinery mediating mitochondrial fusion and fission have been linked to a wide range of pathological conditions, such as insulin resistance and obesity, neurodegenerative diseases and cancer. Here, we provide an update on the molecular mechanisms promoting mitochondrial fusion and fission in mammals and discuss the emerging association of disturbed mitochondrial dynamics with human disease.

Zhong Y., Xu C., Li J., Liang Z., Wang M., Ma C., Jia C., Cao Y., Chen J.

Zhang D., Li F., Sun C., Chen C., Qin H., Wu X., Jiang M., Zhou K., Yao C., Hu Y.

De Bartolo A., Angelone T., Rocca C.

Skvortsova K.A., Baranich T.I., Omarova Z.M., Kharlamov D.A., Bicherova I.A., Glinkina V.V., Sukhorukov V.S.

As is known mitochondria are not static organelles, and depending on the metabolism of the cell they are capable of undergoing fission or fusion processes. These transformations are collectively termed mitochondrial dynamics and determine the quantity, shape, and size of these organelles in the cell. In recent decades, interest in studying the mechanisms of mitochondrial dynamics under normal and pathological conditions has increased. Proteins that regulate the fission and fusion of mitochondrial membranes, which are activated depending on energy needs, have become known. An imbalance in the processes of division and fusion can lead to changes in cell metabolism, disruption of its numerous functions and adaptive capabilities. Recently, more and more studies have appeared on the effect of hypoxia on mitochondrial dynamics. As a rule, the connection between acute hypoxia and the levels of proteins that regulate mitochondrial fission and fusion in the cell is considered. The purpose of this article is to review the literature on changes in mitochondrial dynamics under hypoxia in embryonic and mature tissues, as well as to analyze prospects of further study of the mechanisms of mitochondrial dynamics under conditions of reduced oxygen concentration.

Fedotova E.I., Berezhnov A.V., Popov D.Y., Shitikova E.Y., Vinokurov A.Y.

Atherosclerosis is a complex inflammatory process associated with high-mortality cardiovascular diseases. Today, there is a growing body of evidence linking atherosclerosis to mutations of mitochondrial DNA (mtDNA). But the mechanism of this link is insufficiently studied. Atherosclerosis progression involves different cell types and macrophages are one of the most important. Due to their high plasticity, macrophages can demonstrate pro-inflammatory and pro-atherogenic (macrophage type M1) or anti-inflammatory and anti-atherogenic (macrophage type M2) effects. These two cell types, formed as a result of external stimuli, differ significantly in their metabolic profile, which suggests the central role of mitochondria in the implementation of the macrophage polarization route. According to this, we assume that mtDNA mutations causing mitochondrial disturbances can play the role of an internal trigger, leading to the formation of macrophage M1 or M2. This review provides a comparative analysis of the characteristics of mitochondrial function in different types of macrophages and their possible associations with mtDNA mutations linked with inflammation-based pathologies including atherosclerosis.

Hong C., Wang L., Zhou X., Zou L., Xiang X., Deng H., Li Q., Wu Y., Liu L., Li T.

ABSTRACTBackgroundNeuroinflammation is one of the essential pathogeneses of cognitive damage suffering from sepsis‐associated encephalopathy (SAE). Lots of evidences showed the microglia presented mitochondrial fragmentation during SAE. This study investigated the protective effects and novel mechanisms of inhibiting microglia mitochondrial fragmentation via mitochondrial division inhibitor 1 (Mdivi‐1) on cognitive damage in SAE.MethodsThe SAE model was performed by cecal ligation and puncture (CLP), and Mdivi‐1 was administrated via intraperitoneal injection. Morris water maze was performed to assess cognitive function. Mitochondrial morphology was observed by electron microscope or MitoTracker staining. The qRT‐PCR, immunofluorescence staining, and western blots were used to detect the inflammatory factors and protein content, respectively. Flow cytometry was used to detect the polarization of hippocampal microglia. Bioinformatics analysis was used to verify hypotheses.ResultsMdivi‐1 administration alleviated sepsis‐induced mitochondrial fragmentation, microglia activation, polarization, and cognitive damage. The mechanisms study showed neuroinflammation and oxidative stress were suppressed via NF‐κB and Keap1/Nrf2/HO‐1 pathways following Mdivi‐1 administration; meanwhile, pyroptosis in microglia was reduced, which was associated with enhanced autophagosome formation via p62 elevation following Mdivi‐1 administration.ConclusionInhibition of microglia mitochondrial fragmentation is beneficial to SAE cognitive disturbance, the mechanisms are related to alleviating neuroinflammation, oxidative stress, and pyroptosis.

Ge W., Zhang X., Lin J., Wang Y., Zhang X., Duan Y., Dai X., Zhang J., Zhang Y., Jiang M., Qiang H., Zhao Z., Zhang X., Sun D.

AbstractDoxorubicin, a representative drug of the anthracycline class, is widely used in cancer treatment. However, Doxorubicin-induced cardiotoxicity (DIC) presents a significant challenge in its clinical application. Mitochondrial dysfunction plays a central role in DIC, primarily through disrupting mitochondrial dynamics. This study aimed to investigate the impact of Rnd3 (a Rho family GTPase 3) on DIC, with a focus on mitochondrial dynamics. Cardiomyocyte-specific Rnd3 transgenic mice (Rnd3-Tg) and Rnd3LSP/LSP mice (N-Tg) were established for in vivo experiments, and adenoviruses harboring Rnd3 (Ad-Rnd3) or negative control (Ad-Control) were injected in the myocardium for in vitro experiments. The DIC model was established using wild-type, N-Tg, and Rnd3-Tg mice, with subsequent intraperitoneal injection of Dox for 4 weeks. The molecular mechanism was explored through RNA sequencing, immunofluorescence staining, co-immunoprecipitation assay, and protein-protein docking. Dox administration induced significant mitochondrial injury and cardiac dysfunction, which was ameliorated by Rnd3 overexpression. Further, the augmentation of Rnd3 expression mitigated mitochondrial fragmentation which is mediated by dynamin-related protein 1 (Drp1), thereby ameliorating the PANoptosis (pyroptosis, apoptosis, and necroptosis) response induced by Dox. Mechanically, the interaction between Rnd3 and Rho-associated kinase 1 (Rock1) may impede Rock1-induced Drp1 phosphorylation at Ser616, thus inhibiting mitochondrial fission and dysfunction. Interestingly, Rock1 knockdown nullified the effects of Rnd3 on cardiomyocytes PANoptosis, as well as Dox-induced cardiac remodeling and dysfunction elicited by Rnd3. Rnd3 enhances cardiac resilience against DIC by stabilizing mitochondrial dynamics and reducing PANoptosis. Our findings suggest that the Rnd3/Rock1/Drp1 signaling pathway represents a novel target for mitigating DIC, and modulating Rnd3 expression could be a strategic approach to safeguarding cardiac function in patients undergoing Dox treatment.

Xu M., Feng P., Yan J., Li L.

Chronic obstructive pulmonary disease (COPD) is a prevalent chronic respiratory disease worldwide. Mitochondrial quality control mechanisms encompass processes such as mitochondrial biogenesis, fusion, fission, and autophagy, which collectively maintain the quantity, morphology, and function of mitochondria, ensuring cellular energy supply and the progression of normal physiological activities. However, in COPD, due to the persistent stimulation of harmful factors such as smoking and air pollution, mitochondrial quality control mechanisms often become deregulated, leading to mitochondrial dysfunction. Mitochondrial dysfunction plays a pivotal role in the pathogenesis of COPD, contributing toinflammatory response, oxidative stress, cellular senescence. However, therapeutic strategies targeting mitochondria remain underexplored. This review highlights recent advances in mitochondrial dysfunction in COPD, focusing on the role of mitochondrial quality control mechanisms and their dysregulation in disease progression. We emphasize the significance of mitochondria in the pathophysiological processes of COPD and explore potential strategies to regulate mitochondrial quality and improve mitochondrial function through mitochondrial interventions, aiming to treat COPD effectively. Additionally, we analyze the limitations and challenges of existing therapeutic strategies, aiming to provide new insights and methods for COPD treatment.

Luo X., He C., Yang B., Yin S., Li K.

The study was designed to investigate the impact of N6-methyladenosine (m6A) writer Wilms tumor 1-associated protein (WTAP) on the progression of atherosclerosis (AS) and to further elucidate its possible regulatory mechanism. The m6A levels and WTAP expressions were initially assessed through RIP, qRT-PCR, and western blotting. An in vitro model of AS was constructed by ox-LDL treatment in RAW264.7 cells. Next, the impact of WTAP on macrophage pyroptosis and M1 polarization was evaluated. The relationship between WTAP and NLRP3 was then investigated using m6A modification quantification and RIP-qPCR assay. To investigate the effect of WTAP on AS development in vivo, we created an ApoE−/−mouse model of AS by feeding high-fat diet (HFD). Furthermore, the influence of WTAP on macrophage pyroptosis and M1 polarization through NLRP3 was explored by NLRP3 overexpression AAV injection. Here, we found that WTAP was significantly upregulated in peripheral blood mononuclear cells (PBMCs) from AS patients, accompanied by increased total m6A methylation levels. The silencing of WTAP suppressed macrophage pyroptosis and M1 polarization induced by ox-LDL and also ameliorated aortic root lesion damage in AS mice. Mechanistically, m6A modification mediated by WTAP enhanced NLRP3 mRNA stabilization, thereby upregulating NLRP3 expression. Overexpression of NLRP3 was found to enhance macrophage pyroptosis and M1 polarization, contributing to the progression of AS. In conclusion, our findings suggest that WTAP knockdown mitigated AS progression by modulating NLRP3 in an m6A-dependent manner. Our study proposes that targeting WTAP could be a potential preventive and therapeutic strategy for AS patients.

Wang H., Tang R., Pan Q., Yin Q., Feng J., Deng L.

Mosalmanzadeh N., Maurmann R.M., Davis K., Schmitt B.L., Makowski L., Pence B.D.

AbstractAtherosclerosis, a major contributor to cardiovascular disease, involves lipid accumulation and inflammatory processes in arterial walls, with oxidized low-density lipoprotein (OxLDL) playing a central role. OxLDL is increased during aging and stimulates monocyte transformation into foam cells and induces metabolic reprogramming and pro-inflammatory responses, accelerating atherosclerosis progression and contributing to other age-related diseases. This study investigated the effects of Mdivi-1, a mitochondrial fission inhibitor, and S1QEL, a selective complex I-associated reactive oxygen species (ROS) inhibitor, on OxLDL-induced responses in monocytes. Healthy monocytes isolated from participants were treated with OxLDL, with or without Mdivi-1 or S1QEL, and assessed for metabolic shifts, inflammatory cytokine expression, foam cell formation, and ROS production. OxLDL treatment elevated glycolytic activity (ECAR) and expression of pro-inflammatory cytokines IL1B and CXCL8, promoting foam cell formation and mitochondrial ROS (mtROS) production. Mdivi-1 and S1QEL effectively reduced OxLDL-induced glycolytic reprogramming, inflammatory cytokine levels, and foam cell formation while limiting mtROS. These findings suggest that both Mdivi-1 and S1QEL modulate key monocyte responses to OxLDL, providing insights into potential therapeutic approaches for age-related diseases.

Li W., Huang Y., Liu J., Zhou Y., Sun H., Fan Y., Liu F.

Salis Torres A., Lee J., Caporali A., Semple R.K., Horrocks M.H., MacRae V.E.

Individuals diagnosed with Parkinson’s disease (PD) often exhibit heightened susceptibility to cardiac dysfunction, reflecting a complex interaction between these conditions. The involvement of mitochondrial dysfunction in the development and progression of cardiac dysfunction and PD suggests a plausible commonality in some aspects of their molecular pathogenesis, potentially contributing to the prevalence of cardiac issues in PD. Mitochondria, crucial organelles responsible for energy production and cellular regulation, play important roles in tissues with high energetic demands, such as neurons and cardiac cells. Mitochondrial dysfunction can occur in different and non-mutually exclusive ways; however, some mechanisms include alterations in mitochondrial dynamics, compromised bioenergetics, biogenesis deficits, oxidative stress, impaired mitophagy, and disrupted calcium balance. It is plausible that these factors contribute to the increased prevalence of cardiac dysfunction in PD, suggesting mitochondrial health as a potential target for therapeutic intervention. This review provides an overview of the physiological mechanisms underlying mitochondrial quality control systems. It summarises the diverse roles of mitochondria in brain and heart function, highlighting shared pathways potentially exhibiting dysfunction and driving cardiac comorbidities in PD. By highlighting strategies to mitigate dysfunction associated with mitochondrial impairment in cardiac and neural tissues, our review aims to provide new perspectives on therapeutic approaches.

Lin L., Wei J., Xue J., Fan G., Zhu W., Zhu Y., Wu R.

Autoimmune myocarditis (AM) is characterized by an intricate inflammatory response within the myocardium. Dynamin-related protein 1 (Drp1), a pivotal modulator of mitochondrial fission, plays a role in the pathogenesis of various diseases. A myosin-induced experimental autoimmune myocarditis (EAM) mouse model was successfully established. Flow cytometry was employed to detect M1/M2-like macrophages. Mitochondrial fragmentation was assessed using Mito-Tracker Red CMXRos. Drp1 was upregulated and activated in EAM mice. Depletion of Drp1 was observed to mitigate inflammation, macrophage infiltration and M1 polarization within the cardiac tissue of EAM mice. In M1-like macrophages derived from the hearts of EAM mice, Drp1 was found to promote mitochondrial fission and diminish mitochondrial fusion. Furthermore, the depletion of Drp1 reduced the NF-κB-related pro-inflammatory response in EAM-associated M1-like macrophages. Drp1 drives mitochondrial fission in macrophages, driving their M1 polarization and the subsequent inflammatory response. Drp1 may represent an effective target for the prevention and treatment of AM.

Mackay C.D., Meechem M.B., Patel V.B.

Macrophages are a dynamic cell type of the immune system implicated in the pathophysiology of vascular diseases and are a major contributor to pathological inflammation. Excessive macrophage accumulation, activation, and polarization is observed in aortic aneurysm (AA), atherosclerosis, and pulmonary arterial hypertension. In general, macrophages become activated and polarized to a pro-inflammatory phenotype, which dramatically changes cell behavior to become pro-inflammatory and infiltrative. These cell types become cumbersome and fail to be cleared by normal mechanisms such as autophagy. The result is a hyper-inflammatory environment causing the recruitment of adjacent cells and circulating immune cells to further augment the inflammatory response. In AA, this leads to excessive ECM degradation and chemokine secretion, ultimately causing macrophages to dominate the immune cell landscape in the aortic wall. In atherosclerosis, monocytes are recruited to the vascular wall, where they polarize to the pro-inflammatory phenotype and induce inflammatory pathway activation. This leads to the development of foam cells, which significantly contribute to neointima and necrotic core formation in atherosclerotic plaques. Pro-inflammatory macrophages, which affect other vascular diseases, present with fragmented mitochondria and corresponding metabolic dysfunction. Targeting macrophage mitochondrial dynamics has proved to be an exciting potential therapeutic approach to combat vascular disease. This review will summarize mitochondrial and metabolic mechanisms of macrophage activation, polarization, and accumulation in vascular diseases.