Function In Cells Research Articles

Clec4e deletion in cardiac resident cells leads to smaller infarct size and better cardiac remodeling following myocardial ischemia-reperfusion injury

Abstract Introduction Clec4e-signalling in cardiac resident cells and circulating immune cells stimulates recruitment of proinflammatory leukocytes to infarcted myocardium following ischemia reperfusion injury (I/R) and contributes to ischemic myocardial damage. Clec4e deletion is associated with reduced cardiac injury and better left ventricular structural and functional remodeling. The mechanisms of this cardioprotective effect remain unknown. Research question: We investigated whether Clec4e gene function in cardiac resident cells vs infiltrating immune cells mediates cardioprotection during myocardial ischemia-reperfusion injury. Methods We generated chimeric mice by performing bone marrow transfer in wild type (WT) C57Bl6/J and C57Bl6/J Clec4e-/- mice. Following total body irradiation using 9.5 Gy in 8w-old WT and Clec4e-/- receptor mice, 5 x 10^6 bone marrow cells originating from Clec4e-/- and WT donor mice, respectively, were injected IV. Four weeks later, mice were anesthetized and subjected to ischemia reperfusion injury (I/R) by transient occlusion of the LAD for 60 min. Troponin levels were measured at 90 min post I/R and 7T-magnetic resonance imaging with late gadolinium enhancement (LGE) for infarct size evaluation was performed at 24 hours and 28 days post I/R without LGE. Mice were euthanized at 28 days post I/R and the heart and long shaft bones were processed for postmortem immunohistochemistry and analysis of BM chimerism. Results Immunohistochemical analysis of CLEC4E expression on a bone marrow smear 8 w post bone marrow transfer confirmed successful BM chimerism (7% vs 99%, p<0.01). TnI levels at 90 minutes and LGE assessed infarct size on MRI at 24 hours were not significantly different between groups (n=17 in both groups) (42.1 vs 48.4 ng/ml, and 25.2 vs 31.5% of LVmass in Clec4e-/- mice with WT bone marrow versus in WT mice with Clec4e-/- BM, respectively) suggesting similar myocardial damage . After 28 days, mean LV end diastolic volumes (43µL vs 55µL), and mean end systolic volumes (13µL vs 25µL) were significantly (p<0,05) smaller in Clec4e-/- mice with WT bone marrow resulting in better preserved global LV function (LVEF 62% vs 47%, p<0,05, fig A). Infarct size, semiquantitatively assessed using planimetry on Sirius red stains showed a smaller infarct size in the Clec4e-/- mice with WT bone marrow (6.9% vs 19.8%, p<0.01). Figure B shows a representative example of LGE infarct size to scar tissue on MRI and Sirius red staining. Conclusion Clec4e gene deletion in cardiac resident cells, but not in infiltrating hematopoietic immune cells is associated with better functional and structural remodeling after myocardial I/R. Inhibition of Clec4e signaling via blocking antibodies or small molecule inhibitors in cardiac myocytes might be a promising cardioprotective strategy.

Genetically Engineered Clostridium Prevents Perivascular Adipose Tissue and Endothelial Senescence and Dysfunction in Aging

Abstract Introduction (Peri)vascular senescence is a bona fide risk for several aging-associated diseases that threatens healthspan. Gut microbiome may be one of triggers that promotes vascular diseases as host ages. However, the interplay between vascular senescence and gut microbiome is largely unknown. Our recent studies revealed an increase in gut-derived phenylacetic acid (PAA) in the aging population (TwinsUK Aging Cohort, n=7,303) and aged mice. Our preliminary shotgun metagenomics also showed that ppfor-harboring Clostridium sp. ASF356 age-dependently generates PAA, which induces perivascular adipose tissue (PVAT) and endothelial cell (EC) senescence and dysfunction in old mice. Yet, it remains unclear whether and how genetic engineering of Clostridium sp. ASF356 (by depleting ppfor gene) can prevent aortic PVAT-EC senescence and restore vascular function in aging. Methods For bacterial genetic engineering, we depleted ppfor gene in Clostridium ASF356 by ClosTron technique and further mono-colonized aged mice (24-months old) and germ-free mice, as control, to reduce plasma PAA and thereby prevent aortic PVAT-EC senescence and improve endothelial dysfunction. Results As a proof of the concept, our studies exhibited that mono-colonization of germ-free mice with wild-type Clostridium sp. ASF356 markedly elevates plasma PAA levels. It was accompanied by hallmarks of aortic PVAT-EC senescence, including increased DNA damage (↑ γ-H2A.X phosphorylation), heightened SASP (↑ IL-6 and VCAM1), and proliferative arrest (↑ p16INK4a and p21WAF1/Cip1). Additionally, our findings revealed upreglation of Notch1 in PVAT, contributing to reduced energy supply (↓ UCP1) and augmented senescence-messaging secretome (↑ IL-6) towards ECs. Our further studies revealed that mono-colonization of aged mice (pre-treated with antibiotics) with Δppfor Clostridium ASF356 mutants intriguingly resulted in decreased plasma PAA levels. This intervention led to the rescues of cellular senescence in both aortic PVAT and ECs, consequently improving vascular function. Specifically, mice subjected to this treatment exhibited a significant reduction in SA-β-galactosidase+ cells, as well as decreased levels of γ-H2A.X phosphorylation, p16INK4a, p21WAF1/Cip1, and IL-6 in their aortic PVAT and ECs compared to wild-type aged mice. Conclusions The current study suggests that genetically engineered Δppfor Clostridium ASF356 mutants reverse cellular senescence and restore function in aortic PVAT and endothelial cells, highlighting the potential for targeted gut microbiome manipulation as an innovative senotherapy to combat vascular aging.

Restoration of autophagy reduces diabetes-induced endothelial dysfunction

Abstract Introduction Diabetes leads to endothelial dysfunction, a main determinant of several cardiovascular diseases. The molecular mechanisms underlying the effects of hyperglycemia in endothelial cells are not fully characterized. Autophagy, the intracellular process by which the cell digests and recycles senescent or damaged cytoplasmic elements, exerts cardiovascular protective effects, limiting cardiac and vascular injury in the presence of stress. However, it is unclear how hyperglycemia modulates autophagy in endothelial cells. Purpose In this study, we elucidated the role of autophagy in vascular damage induced by diabetes. We also tested whether the restoration autophagy attenuates diabetes-induced endothelial damage. Methods We evaluated the effects of high-glucose (HG, 30 mM for 6 and 24 hours) on markers of endothelial function, autophagy, autophagic flux, and mitophagy in human umbilical endothelial cells (HUVEC) in vitro and in mesenteric arteries from wild-type mice (WT) ex vivo. We tested the effects of autophagy reactivation using the natural polyamine spermidine or ATG7 overexpression (ATG7ov) on apoptosis and angiogenesis in HUVEC treated with HG. Vascular reactivity experiments in the presence of autophagy activation were performed in HG-treated mouse mesenteric arteries and human saphenous veins from patients with peripheral artery disease. Finally, we evaluated the level of autophagy in the mammary arteries of newly discovered diabetic patients undergoing coronary artery bypass graft surgery. Results We found that HG reduces autophagy (0.6 fold p<0.05) and mitophagy (1.5 fold p<0.001) in HUVECs. We also demonstrated that endothelial cells undergoing hyperglycemia fail to activate autophagy under hypoxic conditions (0.6 fold p<0.05). Reactivation of autophagy by ATG7ov rescues apoptosis (0.52 fold p<0.05) and angiogenesis (2.3 fold p<0.05) in HUVEC treated with HG. We further observed that HG exacerbates endothelial dysfunction in a mouse model of genetic inhibition (Beclin 1 +/- mice), compared to WT mice (-19.16 % +-4.97 SEM vs -48.39 % +-2.18 SEM p<0.001). Mechanistically, HG increases cellular acetylation status (0.7 fold p<0.05) and activates p300 (1 fold p<0.05), an autophagy inhibitor. ATG7ov or spermidine, a p300 inhibitor, rescue endothelial-dependent relaxation in mesenteric arteries of WT mice treated with HG (ATG7ov -62.48 % +-5.16 SEM; SP -63.01 +-3.22 SEM; HG -40.67 % +-3.82 p<0.001). Finally, we observed reduced levels of autophagy in mammary arteries from diabetic patients and demonstrated that SP improves vascular function in human saphenous veins (-37.6 % +-12.76 SEM vs -12.52 % +-5.6 SEM p<0.001). Conclusion Our results suggest that the impairment of autophagy is a strong contributor of diabetes induced-endothelial dysfunction. Targeting autophagy may represent a valid therapeutic strategy to counteract the cardiovascular consequences of metabolic stress.

Development of a high-throughput screening system targeting the protein-protein interactions between PRL and CNNM

Phosphatase of regenerating liver (PRL) is an oncogenic protein that promotes tumor progression by directly binding to cyclin M (CNNM) membrane proteins and inhibiting their Mg2+ efflux activity. In this study, we have developed a high-throughput screening system to detect the interactions between PRL and CNNM proteins based on homogenous time-resolved fluorescence resonance energy transfer (HTR-FRET, HTRF). We optimized the tag sequences attached to the recombinant proteins of the CNNM4 CBS domains and PRL3 lacking the carboxyl terminal CAAX motif, and successfully detected the interaction by observing the FRET signal in the mixture of the tagged proteins and fluorophore-conjugated antibodies. Moreover, we performed compound library screening using this system and discovered several compounds that could efficiently inhibit the PRL-CNNM interaction. Characterization of one candidate compound revealed that it was relatively stable compared with thienopyridone, a known inhibitor of the PRL-CNNM interaction. The candidate compound can also inhibit PRL function in cells: suppression of CNNM-dependent Mg2+ efflux, and has sufficient in vitro drug metabolism and pharmacokinetic properties. Overall, these results demonstrate the effectiveness of this screening system for identifying novel inhibitors of the PRL-CNNM interaction, which could contribute to the development of novel anti-cancer drugs.

Role of Sphingosine-1-Phosphate Signaling Pathway in Pancreatic Diseases

Sphingosine-1-phosphate (S1P) is a sphingolipid metabolic product produced via the phosphorylation of sphingosine by sphingosine kinases (SPHKs), serving as a powerful modulator of various cellular processes through its interaction with S1P receptors (S1PRs). Currently, this incompletely understood mechanism in pancreatic diseases including pancreatitis and pancreatic cancer, largely limits therapeutic options for these disorders. Recent evidence indicates that S1P significantly contributes to pancreatic diseases by modulating inflammation, promoting pyroptosis in pancreatic acinar cells, regulating the activation of pancreatic stellate cells, and affecting organelle functions in pancreatic cancer cells. Nevertheless, no review has encapsulated these advancements. Thus, this review compiles information about the involvement of S1P signaling in exocrine pancreatic disorders, including acute pancreatitis, chronic pancreatitis, and pancreatic cancer, as well as prospective treatment strategies to target S1P signaling for these conditions. The insights presented here possess the potential to offer valuable guidance for the implementation of therapies targeting S1P signaling in various pancreatic diseases.

Unfractionated Heparin Enhances Sepsis Prognosis Through Inhibiting Drp1‐Mediated Mitochondrial Quality Imbalance

AbstractUnfractionated heparin (UFH) is commonly used as an anticoagulant in sepsis treatment and has recently been found to have non‐anticoagulant effects, but underlying mechanisms remain unclear. This retrospective clinical data showed that UFH has significant protective effects in sepsis compared to low‐molecular‐weight heparin and enoxaparin, indicating potential benefits of its non‐anticoagulant properties. Recombinant protein chip screening, surface plasmon resonance, and molecular docking data demonstrated that UFH specifically bound to the cytoplasmic Drp1 protein through its zone 2 non‐anticoagulant segment. In‐vitro experiments verified that UFH's specific binding to Drp1 suppressed Drp1 translocation to mitochondria following “sepsis” challenge, thereby improving mitochondrial morphology, function and metabolism in vascular endothelial cells. Consequently, UHF comprehensively protected mitochondrial quality, thus reducing vascular leakage and improving prognosis in a sepsis rat model. These findings highlight the potential of UFH as a sepsis treatment strategy targeting non‐anticoagulation mechanism.

Optogenetically engineered Septin-7 enhances immune cell infiltration of tumor spheroids

Chimeric antigen receptor T cell therapies have achieved great success in eradicating some liquid tumors, whereas the preclinical results in treating solid tumors have proven less decisive. One of the principal challenges in solid tumor treatment is the physical barrier composed of a dense extracellular matrix, which prevents immune cells from penetrating the tissue to attack intratumoral cancer cells. Here, we improve immune cell infiltration into solid tumors by manipulating septin-7 functions in cells. Using protein allosteric design, we reprogram the three-dimensional structure of septin-7 and insert a blue light-responsive light-oxygen-voltage-sensing domain 2 (LOV2), creating a light-controllable septin-7-LOV2 hybrid protein. Blue light inhibits septin-7 function in live cells, inducing extended cell protrusions and cell polarization, enhancing cell transmigration efficiency through confining spaces. We genetically edited human natural killer cell line (NK92) and mouse primary CD8+ T-cells expressing the engineered protein, and we demonstrated improved penetration and cytotoxicity against various tumor spheroid models. Our proposed strategy to enhance immune cell infiltration is compatible with other methodologies and therefore, could be used in combination to further improve cell-based immunotherapies against solid tumors.

MSI2 mediates WNT/β-Catenin pathway function in hematopoietic stem cells.

MSI2 mediates WNT/β-Catenin pathway function in hematopoietic stem cells.

PRC2-EZH1 contributes to circadian gene expression by orchestrating chromatin states and RNA polymerase II complex stability.

Circadian rhythmicity of gene expression is a conserved feature of cell physiology. This involves fine-tuning between transcriptional and post-transcriptional mechanisms and strongly depends on the metabolic state of the cell. Together these processes guarantee an adaptive plasticity of tissue-specific genetic programs. However, it is unclear how the epigenome and RNA Pol II rhythmicity are integrated. Here we show that the PcG protein EZH1 has a gateway bridging function in postmitotic skeletal muscle cells. On the one hand, the circadian clock master regulator BMAL1 directly controls oscillatory behavior and periodic assembly of core components of the PRC2-EZH1 complex. On the other hand, EZH1 is essential for circadian gene expression at alternate Zeitgeber times, through stabilization of RNA Polymerase II preinitiation complexes, thereby controlling nascent transcription. Collectively, our data show that PRC2-EZH1 regulates circadian transcription both negatively and positively by modulating chromatin states and basal transcription complex stability.

Vital Dye Uptake of YO-PRO-1 and DASPEI Depends Upon Mechanoelectrical Transduction Function in Zebrafish Hair Cells.

Vital dyes allow the visualization of cells in vivo without causing tissue damage, making them a useful tool for studying lateral line and inner ear hair cells in living zebrafish and other vertebrates. FM1-43, YO-PRO-1, and DASPEI are three vital dyes commonly used for hair cell visualization. While it has been established that FM1-43 enters hair cells of zebrafish and other organisms through the mechanoelectrical transduction (MET) channel, the mechanism of entry into hair cells for YO-PRO-1 and DASPEI has not been established despite widespread use. We hypothesize that YO-PRO-1 and DASPEI entry into zebrafish hair cells is MET channel uptake dependent similar to FM1-43. To test this hypothesis, we used both genetic and pharmacologic means to block MET channel function. Genetic based MET channel assays were conducted with two different mechanotransduction defective zebrafish lines, specifically the myo7aa-/- loss of function mutant tc320b (p.Y846X) and cdh23-/- loss of function mutant (c.570-571del). Pharmacologic assays were performed with Gadolinium(III) Chloride (Gad(III)), a compound that can temporarily block mechanotransduction activity. Five-day post fertilization (5dpf) myo7aa-/- and cdh23-/- larvae incubated with FM1-43, YO-PRO-1, and DASPEI all showed nearly absent uptake of each vital dye. Treatment of wildtype zebrafish larvae with Gad(III) significantly reduces uptake of FM1-43, YO-PRO-1, and DASPEI vital dyes. These results indicate that YO-PRO-1 and DASPEI entry into zebrafish hair cells is MET channel dependent similar to FM1-43. This knowledge expands the repertoire of vital dyes that can be used to assess mechanotransduction and MET channel function in zebrafish and other vertebrate models of hair cell function.

Excess Potassium Promotes Autophagy to Maintain the Immunosuppressive Capacity of Myeloid-Derived Suppressor Cells Independent of Arginase 1.

Potassium ions (K+) are critical electrolytes that regulate multiple functions in immune cells. Recent studies have shown that the elevated concentration of extracellular potassium in the tumor interstitial fluid limits T cell effector function and suppresses the anti-tumor capacity of tumor-associated macrophages (TAMs). The effect of excess potassium on the biology of myeloid-derived suppressor cells (MDSCs), another important immune cell component of the tumor microenvironment (TME), is unknown. Here, we present data showing that increased concentrations of potassium chloride (KCl), as the source of K+ ions, facilitate autophagy by increasing the expression of the autophagosome marker LC3β. Simultaneously, excess potassium ions significantly decrease the expression of arginase I (Arg I) and inducible nitric oxide synthase (iNOS) without reducing the ability of MDSCs to suppress T cell proliferation. Further investigation reveals that excess K+ ions decrease the expression of the transcription factor C/EBP-β and alter the expression of phosphorylated kinases. While excess K+ ions downregulated the expression levels of phospho-AMPKα (pAMPKα), it increased the levels of pAKT and pERK. Additionally, potassium increased mitochondrial respiration as measured by the oxygen consumption rate (OCR). Interestingly, all these alterations induced by K+ ions were abolished by the autophagy inhibitor 3-methyladenine (3-MA). Our results suggest that hyperosmotic stress caused by excess K+ ions regulate the mitochondrial respiration and signaling pathways in MDSCs to trigger the process of autophagy to support MDSCs' immunosuppressive function by mechanisms independent of Arg I and iNOS. Overall, our in vitro and ex vivo findings offer valuable insights into the adaptations of MDSCs within the K+ ion-rich TME, which has important implications for MDSCs-targeted therapies.

Abstract B046: Enhanced immune cell engineering utilizing a novel, effective intracellular delivery method for introduction of diverse cargo types

Abstract Engineered immune cell therapies have great potential to revolutionize cancer therapeutics and progress has been made in developing both engineering and manufacturing methodologies. However, limitations remain in some areas including long manufacturing times, potential for cell exhaustion, and limited access to the disease site as in the case for solid tumors. In addition, some immune cell types such as monocytes, B cells, and gamma delta T cells have remained difficult to engineer.Portal has developed a novel implementation of mechanoporation technology using a silicon membrane with pores which enables deformation of the cell and poration of the cell membrane, allowing for diffusion of any cargo, charged or uncharged, into the cell. Mechanoporation is a gentle intracellular delivery technique which preserves cell viability and function in cells (DiTommaso, et al PNAS 2018) and has the potential to shorten manufacturing time as well as allow for introduction of key therapy enhancing factors via transient modifications shortly before therapy administration. Portal has established methodology for cytoplasmic introduction of many diverse cargo including mRNA, circular RNA, siRNA, proteins, peptides, and CRISPR RNPs to primary immune cells, including both unstimulated and activated T cells, B cells, NK cells, monocytes and iPSCs. The Portal technology is easily scalable, enabling both research scale (1e6 - 5e7 cells) and process scale (over 1e9 cells) deliveries. Editing and RNA expression efficiencies are above 80% with viability maintained at 70% or above. We have demonstrated sustained expression of circular RNA, and have successfully delivered an mRNA CAR. Cargo can easily be multiplexed with equivalent delivery efficiencies across cargo classes. Portal’s methodology is gentle and effective enough to be utilized multiple times within a therapeutic workflow. For example, we have demonstrated high editing efficiencies in unstimulated T cells, followed by rapid expansion for 7 days and subsequent mRNA delivery at clinical scale - yielding over 50% knockout and 90% mRNA expression. Portal’s technology and approach has the potential to further advance immune cell therapy developments, particularly in multiplexed engineering approaches involving simultaneous delivery of multiple cargos. Coupled with Portal’s compatibility with diverse immune cell types and next generation cargos, such as circRNA, we believe this simple approach to intracellular delivery can dramatically reduce manufacturing time and cost, easily integrate into existing clinical equipment and enable unique enhancements that underpin a new generation of therapeutics. Citation Format: Zhihui Song, Eleni Rogers, Sophia Hirsch, Andrew Larocque, Darby Kreienberg, Rachel Conover, Jacquelyn Hanson, Alec Barclay, Mathias Pawlak, Armon Sharei. Enhanced immune cell engineering utilizing a novel, effective intracellular delivery method for introduction of diverse cargo types [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2024 Oct 18-21; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2024;12(10 Suppl):Abstract nr B046.

Hyperbaric oxygen rapidly produces intracellular bioenergetics dysfunction in human pulmonary cells

Hyperoxic exposure lasting days alters mitochondrial bioenergetic and dynamic functions in pulmonary cells as indices of oxygen toxicity. The aim of this study was to examine effects of short duration hyperbaric and hyperoxic exposures to induce oxygen toxicity similarly. Cultured human lung microvascular endothelial cells, human pulmonary artery endothelial cells and A549 cells were exposed to hyperoxia (∼5 % CO2 equivalent, balance O2) under hyperbaric conditions (4.8 ATA) for 1 and 4 h. Measures of mitochondrial dynamics, inner membrane potential, mitochondrial respiration, the intracellular distribution of bioenergetic capacity and respiration complex protein levels were then quantified. Exposures resulted in altered mitochondrial motility, presence of inhomogeneities in respiration parameters, loss of inner membrane potential, and changes in intracellular partitioning of ATP-linked respiration. Changes in the levels of respiration complex protein levels were also found. The combination of hyperoxic exposure with hyperbaric conditions rapidly produced changes in mitochondrial dynamics and bioenergetics in pulmonary cells. These changes are consistent with the onset of pulmonary oxygen toxicity previously known to result from long duration exposure to hyperoxia alone. These findings suggest health caution is warranted in environmental settings in which both hyperoxic and hyperbaric conditions are present. The synergism of hyperoxia and hyperbaria for rapid induction of oxygen toxicity in cellular models has utility for the study of mechanistic determinants of oxygen toxicity, testing of putative therapeutics, and associated investigations of mitochondrial dysfunction.

Imatinib decreases germ cell survival and germline stem cell proliferation in rodent testis ex vivo and in vitro.

Imatinib and dasatinib are tyrosine kinase inhibitors (TKIs) increasingly used to treat several diseases in both children and adults at fertile age. We have previously shown that imatinib has adverse effects on developing testis, and imatinib-treated male patients have been reported to have reduced sperm counts. However, the cellular level effects of imatinib and dasatinib on adult male germ cells and germline stem cells (mGSCs) have not been thoroughly investigated. To analyze whether imatinib or dasatinib exposure ex vivo and in vitro is harmful to adult male rodent germ cells and mGSCs. Seminiferous tubule segments of adult male mouse or rat were cultured in the presence or the absence of imatinib or dasatinib. Stage-specific effects were monitored by 3H-thymidine incorporation assay (DNA synthesis), immunohistochemistry (cleaved Caspase-3; apoptosis), immunofluorescence (KI67, GFRα1, STRA8, c-KIT, LIN28A; proliferation and spermatogonial differentiation) and flow cytometry (Hoechst). Mouse mGSCs were exposed to imatinib and dasatinib to study proliferation, apoptosis, and differentiation. Imatinib decreased stage-specific DNA synthesis, and induced apoptosis in cultured rat seminiferous tubule segments. Imatinib also had an adverse effect on mGSC proliferation both in vitro and ex vivo, but did not induce cell death in cultured mGSCs. Imatinib did not impinge on induction of spermatogonial differentiation but suppressed c-KIT expression in nascent differentiating spermatogonia, providing a plausible mechanism for its pro-apoptotic function in spermatogenic cells. Clinically relevant doses of dasatinib did not induce apoptosis in seminiferous tubules but decreased mGSC colony growth in vitro. Imatinib exposure ex vivo and in vitro impinges on male rodent germ cell proliferation and survival. The plausible mechanism in spermatogenic cells is the inhibition of SCF/c-KIT signaling, and reduced expression of c-KIT. Dasatinib did not show significant adverse effects with clinical doses ex vivo but inhibited mGSC colony growth in vitro.

Role of DOCK8 in Cytokine Storm Syndromes

Cytokine storm syndromes (CSS), including hemophagocytic lymphohistiocytosis (HLH), are increasingly recognized as hyperinflammatory states leading to multi-organ failure and death. Familial HLH (FHL) in infancy results from homozygous genetic defects in perforin-mediated cytolysis by CD8 T-lymphocytes and natural killer (NK) cells. Later onset CSS are frequently associated with heterozygous defects in FHL genes, but genetic etiologies for most are unknown. We identified rare DOCK8 variants in CSS patients. We explore the role of CSS patient-derived DOCK8 mutations on cytolytic activity in NK cells. We further study effects of DOCK8 deficiency in murine models of CSS. DOCK8 cDNA from 2 unrelated CSS patients with different missense mutations were introduced into human NK-92 NK cells by foamy virus transduction. NK cell degranulation (CD107a), cytolytic activity against K562 target cells, and interferon-gamma (IFNγ) production were explored by flow cytometry. A third CSS patient DOCK8 mRNA splice acceptor site variant was explored by exon trapping. Dock8-/- mice were assessed for features of CSS (weight loss, splenomegaly, hepatic inflammation, cytopenias, and IFNγ levels) upon challenge with lymphocytic choriomeningitis virus (LCMV) and excess IL-18. Both patient DOCK8 missense mutations decreased cytolytic function in NK cells in a partial dominant-negative fashion in vitro. The patient DOCK8 splice variant disrupted mRNA splicing in vitro. LCMV infection promoted CSS in Dock8-/- mice and interacted with excess IL-18 limiting T-cell numbers while promoting CD8 T-cell hyperactivation. Mutations in DOCK8 may contribute to CSS-like hyperinflammatory states by altering cytolytic function in a threshold model of disease.

A recombinant fragment antigen-binding (Fab) of trastuzumab displays low cytotoxic profile in adult human cardiomyocytes: first evidence and the key implication of FcγRIIA receptor.

Fragment crystallizable gamma receptors (FcγRs) mediate various cellular responses with significant cardiovascular implications. They contribute to the anticancer activity of trastuzumab (TRZ), a recombinant humanized monoclonal antibody that interferes with human epidermal growth factor receptor 2 (HER2), thereby blocking its physiological function in cardiac cells. This is responsible for cardiac complications that hamper TRZ clinical application. In this study we investigated the involvement of FcγRs in the TRZ cardiotoxicity. We used a recombinant antigen-binding fragment (Fab) of TRZ (rFab-HER2) to examine whether the absence of the Fc region resulted in fewer cardiomyocyte toxicity while preserving TRZ's ability to inhibit HER2. When exposed to rFab-HER2, AC16 human adult ventricular cardiomyocytes were less vulnerable to damage and death, than to TRZ. Specifically, TRZ exhibited cytotoxicity at a lower concentration (150 µg/mL, corresponding to ~1 µM) compared to rFab-HER2 (250 µg/mL, corresponding to ~5 µM). Like TRZ, rFab-HER2 negatively modulated HER2 levels in cardiomyocyte (without inducing cytotoxic activity in BJ human fibroblast cells that either did not express or express very low levels of HER2) and inhibited the downstream ERK/AKT cascades. But rFab-HER2 did not alter cardiomyocyte mitochondrial dynamic balance, and affect apoptosis and inflammation, while it limited cytosolic and mitochondrial ROS indicators. On contrary, the Fc region (50-250 μg/mL) exerted direct cytotoxic action on cardiomyocytes (but not on human fibroblasts that lacked Fc receptors). TRZ (150 μg/mL) markedly upregulated the expression level of FcγRIIA (a FcγRs strongly involved in TRZ-induced antibody-dependent cellular toxicity) in cardiomyocytes, whereas the Fab fragment (150 μg/mL) had no effect. Our results demonstrate that Fc region plays an important pathogenic role in TRZ-induced cardiomyocyte toxicity. In addition, targeting FcγRIIA might contribute to the off-target effects of TRZ therapy.

Expression of Myeloperoxidase in Patient-Derived Endothelial Colony-Forming Cells-Associations with Coronary Artery Disease and Mitochondrial Function.

Myeloperoxidase (MPO) plays a critical role in the innate immune response and has been suggested to be a surrogate marker of oxidative stress and inflammation, with elevated levels implicated in cardiovascular diseases, such as atherosclerosis and heart failure, as well as in conditions like rheumatoid arthritis and cancer. While MPO is well-known in leukocytes, its expression and function in human endothelial cells remain unclear. This study investigates MPO expression in patient-derived endothelial colony-forming cells (ECFCs) and its potential association with CAD and mitochondrial function. ECFCs were cultured from the peripheral blood of 93 BioHEART-CT patients. MPO expression and associated functions were examined using qRT-PCR, immunochemistry, flow cytometry, and MPO activity assays. CAD presence was defined using CT coronary angiography (CACS > 0). We report MPO presence in patient-derived ECFCs for the first time. MPO protein expression occurred in 70.7% of samples (n = 41) which had nuclear co-localisation, an atypical observation given its conventional localisation in the granules of neutrophils and monocytes. This suggests potential alternative roles for MPO in nuclear processes. MPO mRNA expression was detected in 66.23% of samples (n = 77). CAD patients had a lower proportion of MPO-positive ECFCs compared to non-CAD controls (57.45% vs. 80%, p = 0.04), a difference that persisted in the statin-naïve sub-cohort (53.85% vs. 84.62%, p = 0.02). Non-CAD patients with MPO expression showed upregulated mitochondrial-antioxidant genes (AIFM2, TXNRD1, CAT, PRDX3, PRDX6). In contrast, CAD patients with MPO gene expression had heightened mROS production and mitochondrial mass and decreased mitochondrial function compared to that of CAD patients without MPO gene expression. MPO is present in the nucleus of ECFCs. In non-CAD ECFCs, MPO expression is linked to upregulated mitochondrial-antioxidant genes, whereas in CAD ECFCs, it is associated with greater mitochondrial dysfunction.

PEP-1-PIN1 Promotes Hippocampal Neuronal Cell Survival by Inhibiting Cellular ROS and MAPK Phosphorylation.

Background: The peptidyl-prolyl isomerase (PIN1) plays a vital role in cellular processes, including intracellular signaling and apoptosis. While oxidative stress is considered one of the primary mechanisms of pathogenesis in brain ischemic injury, the precise function of PIN1 in this disease remains to be elucidated. Objective: We constructed a cell-permeable PEP-1-PIN1 fusion protein and investigated PIN1's function in HT-22 hippocampal cells as well as in a brain ischemic injury gerbil model. Methods: Transduction of PEP-1-PIN1 into HT-22 cells and signaling pathways were determined by Western blot analysis. Intracellular reactive oxygen species (ROS) production and DNA damage was confirmed by DCF-DA and TUNEL staining. Cell viability was determined by MTT assay. Protective effects of PEP-1-PIN1 against ischemic injury were examined using immunohistochemistry. Results: PEP-1-PIN1, when transduced into HT-22 hippocampal cells, inhibited cell death in H2O2-treated cells and markedly reduced DNA fragmentation and ROS production. This fusion protein also reduced phosphorylation of mitogen-activated protein kinase (MAPK) and modulated expression levels of apoptosis-signaling proteins in HT-22 cells. Furthermore, PEP-1-PIN1 was distributed in gerbil hippocampus neuronal cells after passing through the blood-brain barrier (BBB) and significantly protected against neuronal cell death and also decreased activation of microglia and astrocytes in an ischemic injury gerbil model. Conclusions: These results indicate that PEP-1-PIN1 can inhibit ischemic brain injury by reducing cellular ROS levels and regulating MAPK and apoptosis-signaling pathways, suggesting that PIN1 plays a protective role in H2O2-treated HT-22 cells and ischemic injury gerbil model.

Frequency-Dependent Antioxidant Responses in HT-1080 Human Fibrosarcoma Cells Exposed to Weak Radio Frequency Fields.

This study explores the complex relationship between radio frequency (RF) exposure and cancer cells, focusing on the HT-1080 human fibrosarcoma cell line. We investigated the modulation of reactive oxygen species (ROS) and key antioxidant enzymes, including superoxide dismutase (SOD), peroxidase, and glutathione (GSH), as well as mitochondrial superoxide levels and cell viability. Exposure to RF fields in the 2-5 MHz range at very weak intensities (20 nT) over 4 days resulted in distinct, frequency-specific cellular effects. Significant increases in SOD and GSH levels were observed at 4 and 4.5 MHz, accompanied by reduced mitochondrial superoxide levels and enhanced cell viability, suggesting improved mitochondrial function. In contrast, lower frequencies like 2.5 MHz induced oxidative stress, evidenced by GSH depletion and increased mitochondrial superoxide levels. The findings demonstrate that cancer cells exhibit frequency-specific sensitivity to RF fields even at intensities significantly below current safety standards, highlighting the need to reassess exposure limits. Additionally, our analysis of the radical pair mechanism (RPM) offers deeper insight into RF-induced cellular responses. The modulation of ROS and antioxidant enzyme activities is significant for cancer treatment and has broader implications for age-related diseases, where oxidative stress is a central factor in cellular degeneration. The findings propose that RF fields may serve as a therapeutic tool to selectively modulate oxidative stress and mitochondrial function in cancer cells, with antioxidants playing a key role in mitigating potential adverse effects.

MiR-210 as a therapeutic target in diabetes-associated endothelial dysfunction.

MicroRNA (miR)-210 function in endothelial cells and its role in diabetes-associated endothelial dysfunction are not fully understood. We aimed to characterize the miR-210 function in endothelial cells and study its therapeutic potential in diabetes. Two different diabetic mouse models (db/db and Western diet-induced), miR-210 knockout and transgenic mice, isolated vessels and human endothelial cells were used. miR-210 levels were lower in aortas isolated from db/db than in control mice. Endothelium-dependent relaxation (EDR) was impaired in aortas from miR-210 knockout mice, and this was restored by inhibiting miR-210 downstream protein tyrosine phosphatase 1B (PTP1B), mitochondrial glycerol-3-phosphate dehydrogenase 2 (GPD2), and mitochondrial oxidative stress. Inhibition of these pathways also improved EDR in both diabetic mouse models. High glucose reduced miR-210 levels in endothelial cells and impaired EDR in mouse aortas, effects that were reversed by overexpressing miR-210. However, plasma miR-210 levels were not affected in individuals with type 2 diabetes (T2D) following improved glycaemic status. Of note, genetic overexpression using miR-210 transgenic mice and pharmacological overexpression using miR-210 mimic in vivo ameliorated endothelial dysfunction in both diabetic mouse models by decreasing PTP1B, GPD2 and oxidative stress. Genetic overexpression of miR-210 altered the aortic transcriptome, decreasing genes in pathways involved in oxidative stress. miR-210 mimic restored decreased nitric oxide production by high glucose in endothelial cells. This study unravels the mechanisms by which down-regulated miR-210 by high glucose induces endothelial dysfunction in T2D and demonstrates that miR-210 serves as a novel therapeutic target.