Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

Inhibition of Mertk Signaling Enhances Bone Healing after Tooth Extraction

Regeneration of alveolar bone is an essential step in restoring healthy function following tooth extraction. Growth of new bone in the healing extraction socket can be variable and often unpredictable when systemic comorbidities are present, leading to the need for additional therapeutic targets to accelerate the regenerative process. One such target is the TAM family (Tyro3, Axl, Mertk) of receptor tyrosine kinases. These proteins have been shown to help resolve inflammation and maintain bone homeostasis and thus may have therapeutic benefits in bone regeneration following extraction. Treatment of mice with a pan-TAM inhibitor (RXDX-106) led to accelerated alveolar bone fill following first molar extraction in a mouse model without changing immune infiltrate. Treatment of human alveolar bone mesenchymal stem cells with RXDX-106 upregulated Wnt signaling and primed the cells for osteogenic differentiation. Differentiation of human alveolar bone mesenchymal stem cells with osteogenic media and TAM-targeted inhibitor RXDX-106 (pan-TAM), ASP-2215 (Axl specific), or MRX-2843 (Mertk specific) showed enhanced mineralization with pan-TAM or Mertk-specific inhibitors and no change with Axl-specific inhibitor. First molar extractions in Mertk-/- mice had increased alveolar bone regeneration in the extraction socket relative to wild type controls 7 d postextraction. Flow cytometry of 7-d extraction sockets showed no difference in immune cell numbers between Mertk-/- and wild type mice. RNAseq of day 7 extraction sockets showed increased innate immune-related pathways and genes associated with bone differentiation in Mertk-/- mice. Together, these results indicate that TAM receptor signaling, specifically through Mertk, can be targeted to enhance bone regeneration after injury.

Formation and evolution of carbonaceous asteroid Ryugu: Direct evidence from returned samples

Samples of the carbonaceous asteroid Ryugu were brought to Earth by the Hayabusa2 spacecraft. We analyzed 17 Ryugu samples measuring 1 to 8 millimeters. Carbon dioxide-bearing water inclusions are present within a pyrrhotite crystal, indicating that Ryugu's parent asteroid formed in the outer Solar System. The samples contain low abundances of materials that formed at high temperatures, such as chondrules and calcium- and aluminum-rich inclusions. The samples are rich in phyllosilicates and carbonates, which formed through aqueous alteration reactions at low temperature, high pH, and water/rock ratios of <1 (by mass). Less altered fragments contain olivine, pyroxene, amorphous silicates, calcite, and phosphide. Numerical simulations, based on the mineralogical and physical properties of the samples, indicate that Ryugu's parent body formed ~2 million years after the beginning of Solar System formation.

Reactive Oxygen Species and NRF2 Signaling, Friends or Foes in Cancer?

The imbalance between reactive oxygen species (ROS) production and clearance causes oxidative stress and ROS, which play a central role in regulating cell and tissue physiology and pathology. Contingent upon concentration, ROS influence cancer development in contradictory ways, either stimulating cancer survival and growth or causing cell death. Cells developed evolutionarily conserved programs to sense and adapt redox the fluctuations to regulate ROS as either signaling molecules or toxic insults. The transcription factor nuclear factor erythroid 2-related factor 2 (NRF2)-KEAP1 system is the master regulator of cellular redox and metabolic homeostasis. NRF2 has Janus-like roles in carcinogenesis and cancer development. Short-term NRF2 activation suppresses tissue injury, inflammation, and cancer initiation. However, cancer cells often exhibit constitutive NRF2 activation due to genetic mutations or oncogenic signaling, conferring advantages for cancer cells' survival and growth. Emerging evidence suggests that NRF2 hyperactivation, as an adaptive cancer phenotype under stressful tumor environments, regulates all hallmarks of cancer. In this review, we summarized the source of ROS, regulation of ROS signaling, and cellular sensors for ROS and oxygen (O₂), we reviewed recent progress on the regulation of ROS generation and NRF2 signaling with a focus on the new functions of NRF2 in cancer development that reach beyond what we originally envisioned, including regulation of cancer metabolism, autophagy, macropinocytosis, unfolded protein response, proteostasis, and circadian rhythm, which, together with anti-oxidant and drug detoxification enzymes, contributes to cancer development, metastasis, and anticancer therapy resistance.

Bortezomib is an effective enhancer for chemical probe-dependent superoxide detection

Various chemical probes for the detection of reactive oxygen species have been developed to examine oxidative stress associated with different pathologies. L-012, a luminol-based chemiluminescent probe, is widely used to detect extracellular superoxide because of its high sensitivity. We herein demonstrated that the co-application of the peptide boronic acid proteasome inhibitor, bortezomib, with L-012 significantly increased its luminescence without affecting the background. More than a 5-fold increase was detected in the total luminescence of L-012 in both NADPH oxidase-expressing cells and the xanthine oxidase-dependent cell-free superoxide generation system, but not in their background. Therefore, bortezomib increased the signal-to-background ratio and improved the detection of low levels of superoxide. The application of MLN2238, another peptide boronic acid proteasome inhibitor, also enhanced the luminescence of L-012. In contrast, carfilzomib, an epoxyketone proteasome inhibitor, did not increase luminescence, suggesting that the effects of bortezomib depend on the chemical structure of the peptide boronic acid, but not on its pharmacological effects. Bortezomib-induced enhancements appeared to be specific to the detection of superoxide because the detection of H₂O₂ by Amplex Red/HRP was not affected by the application of bortezomib. In the quantitative detection of the superoxide-specific oxidative product 2-hydroxyethidium (2-OH-E⁺), the application of bortezomib resulted in a 2-fold increase in the level of 2-OH-E⁺. Therefore, bortezomib sensitizes the detection of superoxide in both cell-based and cell-free systems, highlighting a novel feature of compounds containing the peptide boronic acid as powerful enhancers for the detection of superoxide.

Early vascular responses to abluminal biodegradable polymer-coated versus circumferential durable polymer-coated newer-generation drug-eluting stents in humans: a pathologic study

Background

Recent clinical trials are testing strategies for short (1–3 months) dual antiplatelet therapy (DAPT) following newer-generation drug-eluting stent (DES) placement. However, the safety of short DAPT regimens is not supported by biological evidence in humans.

Purpose

We sought to evaluate early pathologic responses to newer-generation DES by comparing abluminal biodegradable polymer-coated DES (BP-DES) with circumferential durable polymer-coated DES (DP-DES) in human autopsy cases.

Methods

The study included a total of 37 coronary lesions with thin strut newer-generation DES (DP-DES=23 [XIENCE=18, Resolute Integrity=5] and BP-DES=14 [SYNERGY=9, Ultimaster=5]) with duration of implantation &lt;90 days in 25 autopsy cases. The process of stent healing was precisely evaluated for every single strut in association with underlying tissue characteristics. The degree of strut coverage was defined as follows: grade 0 (bare struts), grade 1 (struts covered with thrombus, fibrin, or other tissues or cells without endothelium), grade 2 (struts covered with single-layered endothelium without underlying smooth muscle cell layers), and grade 3 (struts covered with endothelium and underlying smooth muscle cell layers) (Figure 1).

Results

Duration of implantation was similar in lesions with DP-DES and those with BP-DES (median=20 vs. 17 days). A total of 1986 struts (DP-DES=1261, BP-DES=725) were pathologically analyzed. Focal grade 2 coverage was observed as early as 5 days after the implantation in both stents. Multilevel mixed-effects ordered logistic regression model demonstrated that BP-DES exhibited greater strut coverage compared with DP-DES (odds ratio; 3.50, 95% CI; 1.31–9.41, P=0.013), which remained significant after adjustment for duration of implantation and underlying tissue characteristics (odds ratio; 2.64, 95% CI; 1.04–6.68, P=0.040). The time course of vessel healing assessed as predictive probability of strut coverage (grade 0–3) stratified by duration of implantation is shown in Figure 2. Predictive probability of grade 2 and 3 coverage was comparably limited at 30 days (DP-DES=17.7% vs. BP-DES=29.0%) and increased at 90 days (DP-DES=76.1% vs. BP-DES=85.9%). Both stents showed few inflammation and similar degree of fibrin deposition.

Conclusions

The current first pathologic study on early biological responses to newer-generation DES in humans demonstrated that single-layered endothelial coverage begins in days following the stent placement, and abluminal BP-DES potentially exhibit faster strut coverage with smooth muscle cell infiltration than circumferential DP-DES. Nevertheless, vessel healing remains suboptimal at 30 days in both DP- and BP-DES, which progresses with time to become substantial at 90 days. Our results suggest that very short duration of DAPT for 1 month should be applied with caution, taking into account the trade-off between bleeding and thrombotic risks.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Grant-in-Aid for Scientific Research (C) from the Japan Society for the Promotion of Science

Increased levels of a pro-inflammatory IgG receptor in the midbrain of people with schizophrenia

BACKGROUND

There is growing evidence that neuroinflammation may contribute to schizophrenia neuropathology. Elevated pro-inflammatory cytokines are evident in the midbrain from schizophrenia subjects, findings that are driven by a subgroup of patients, characterised as a "high inflammation" biotype. Cytokines trigger the release of antibodies, of which immunoglobulin G (IgG) is the most common. The level and function of IgG is regulated by its transporter (FcGRT) and by pro-inflammatory IgG receptors (including FcGR3A) in balance with the anti-inflammatory IgG receptor FcGR2B. Testing whether abnormalities in IgG activity contribute to the neuroinflammatory abnormalities schizophrenia patients, particularly those with elevated cytokines, may help identify novel treatment targets.

METHODS

Post-mortem midbrain tissue from healthy controls and schizophrenia cases (n = 58 total) was used to determine the localisation and abundance of IgG and IgG transporters and receptors in the midbrain of healthy controls and schizophrenia patients. Protein levels of IgG and FcGRT were quantified using western blot, and gene transcript levels of FcGRT, FcGR3A and FcGR2B were assessed using qPCR. The distribution of IgG in the midbrain was assessed using immunohistochemistry and immunofluorescence. Results were compared between diagnostic (schizophrenia vs control) and inflammatory (high vs low inflammation) groups.

RESULTS

We found that IgG and FcGRT protein abundance (relative to β-actin) was unchanged in people with schizophrenia compared with controls irrespective of inflammatory subtype. In contrast, FcGRT and FcGR3A mRNA levels were elevated in the midbrain from "high inflammation" schizophrenia cases (FcGRT; p = 0.02, FcGR3A; p < 0.0001) in comparison to low-inflammation patients and healthy controls, while FcGR2B mRNA levels were unchanged. IgG immunoreactivity was evident in the midbrain, and approximately 24% of all individuals (control subjects and schizophrenia cases) showed diffusion of IgG from blood vessels into the brain. However, the intensity and distribution of IgG was comparable across schizophrenia cases and control subjects.

CONCLUSION

These findings suggest that an increase in the pro-inflammatory Fcγ receptor FcGR3A, rather than an overall increase in IgG levels, contribute to midbrain neuroinflammation in schizophrenia patients. However, more precise information about IgG-Fcγ receptor interactions is needed to determine their potential role in schizophrenia neuropathology.

EROS is a selective chaperone regulating the phagocyte NADPH oxidase and purinergic signalling

EROS (essential for reactive oxygen species) protein is indispensable for expression of gp91phox, the catalytic core of the phagocyte NADPH oxidase. EROS deficiency in humans is a novel cause of the severe immunodeficiency, chronic granulomatous disease, but its mechanism of action was unknown until now. We elucidate the role of EROS, showing it acts at the earliest stages of gp91phox maturation. It binds the immature 58 kDa gp91phox directly, preventing gp91phox degradation and allowing glycosylation via the oligosaccharyltransferase machinery and the incorporation of the heme prosthetic groups essential for catalysis. EROS also regulates the purine receptors P2X7 and P2X1 through direct interactions, and P2X7 is almost absent in EROS-deficient mouse and human primary cells. Accordingly, lack of murine EROS results in markedly abnormal P2X7 signalling, inflammasome activation, and T cell responses. The loss of both ROS and P2X7 signalling leads to resistance to influenza infection in mice. Our work identifies EROS as a highly selective chaperone for key proteins in innate and adaptive immunity and a rheostat for immunity to infection. It has profound implications for our understanding of immune physiology, ROS dysregulation, and possibly gene therapy.

NOX1/NADPH oxidase is involved in the LPS-induced exacerbation of collagen-induced arthritis

We investigate as yet an unidentified role of NOX1, a non-phagocytic isoform of the superoxide-generating NADPH oxidase, in immune responses using Nox1-knockout mice (Nox1-KO). The transcripts of NOX1 was expressed in lymphoid tissues, including the spleen, thymus, bone marrow, and inguinal lymphoid nodes. When antibody production after ovalbumin (OVA) immunization was examined, no significant differences were observed in serum anti-OVA IgG levels between wild-type mice (WT) and Nox1-KO. In the experimental asthma, the infiltration of eosinophils and the Th2 cytokine response after the induction of asthma with OVA were similar between the two genotypes. However, the severity and incidence of experimental collagen-induced arthritis (CIA) following the administration of a low dose of endotoxin (LPS) were significantly lower in Nox1-KO. While neither serum levels of autoantibodies nor in vitro cytokine responses were affected by Nox1 deficiency, NOX1 mRNA levels in the spleen significantly increased after the LPS challenge. Among the spleen cells, remarkable LPS-induced upregulation of NOX1 was demonstrated in both CD11b+ monocytes/macrophages and CD11c+ dendritic cells, suggesting that LPS-inducible NOX1 in monocytes/macrophages/dendritic cells may modulate the development of experimental CIA. Therapeutic targeting of NOX1 may therefore control the onset and/or severity of arthritis which is exacerbated by bacterial infection.

1,3-Diradicals Embedded in Curved Paraphenylene Units: Singlet versus Triplet State and In-Plane Aromaticity

Curved π-conjugated molecules and open-shell structures have attracted much attention from the perspective of fundamental chemistry, as well as materials science. In this study, the chemistry of 1,3-diradicals (DRs) embedded in curved cycloparaphenylene (CPPs) structures, DR-(n+3)CPPs (n = 0-5), was investigated to understand the effects of the curvature and system size on the spin-spin interactions and singlet versus triplet state, as well as their unique characteristics such as in-plane aromaticity. A triplet ground state was predicted for the larger 1,3-diradicals, such as the seven- and eight-paraphenylene-unit-containing diradicals DR-7CPP (n = 4) and DR-8CPP (n = 5), by quantum chemical calculations. The smaller-sized diradicals DR-(n+3)CPPs (n = 0-3) were found to possess singlet ground states. Thus, the ground-state spin multiplicity is controlled by the size of the paraphenylene cycle. The size effect on the ground-state spin multiplicity was confirmed by the experimental generation of DR-6CPP in the photochemical denitrogenation of its azo-containing precursor (AZ-6CPP). Intriguingly, a unique type of in-plane aromaticity emerged in the smaller-sized singlet states such as S-DR-4CPP (n = 1), as proven by nucleus-independent chemical shift calculations (NICS) and an analysis of the anisotropy of the induced current density (ACID), which demonstrate that homoconjugation between the 1,3-diradical moiety arises because of the curved and distorted bonding system.

NOX1/NADPH Oxidase Promotes Synaptic Facilitation Induced by Repeated D2 Receptor Stimulation: Involvement in Behavioral Repetition

Repetitive behavior is a widely observed neuropsychiatric symptom. Abnormal dopaminergic signaling in the striatum is one of the factors associated with behavioral repetition; however, the molecular mechanisms underlying the induction of repetitive behavior remain unclear. Here, we demonstrated that the NOX1 isoform of the superoxide-producing enzyme NADPH oxidase regulated repetitive behavior in mice by facilitating excitatory synaptic inputs in the central striatum (CS). In male C57Bl/6J mice, repeated stimulation of D2 receptors induced abnormal behavioral repetition and perseverative behavior. Nox1 deficiency or acute pharmacological inhibition of NOX1 significantly shortened repeated D2 receptor stimulation-induced repetitive behavior without affecting motor responses to a single D2 receptor stimulation. Among brain regions, Nox1 showed enriched expression in the striatum, and repeated dopamine D2 receptor stimulation further increased Nox1 expression levels in the CS, but not in the dorsal striatum. Electrophysiological analyses revealed that repeated D2 receptor stimulation facilitated excitatory inputs in the CS indirect pathway medium spiny neurons (iMSNs), and this effect was suppressed by the genetic deletion or pharmacological inhibition of NOX1. Nox1 deficiency potentiated protein tyrosine phosphatase activity and attenuated the accumulation of activated Src kinase, which is required for the synaptic potentiation in CS iMSNs. Inhibition of NOX1 or β-arrestin in the CS was sufficient to ameliorate repetitive behavior. Striatal-specific Nox1 knockdown also ameliorated repetitive and perseverative behavior. Collectively, these results indicate that NOX1 acts as an enhancer of synaptic facilitation in CS iMSNs and plays a key role in the molecular link between abnormal dopamine signaling and behavioral repetition and perseveration.SIGNIFICANCE STATEMENT Behavioral repetition is a form of compulsivity, which is one of the core symptoms of psychiatric disorders, such as obsessive-compulsive disorder. Perseveration is also a hallmark of such disorders. Both clinical and animal studies suggest important roles of abnormal dopaminergic signaling and striatal hyperactivity in compulsivity; however, the precise molecular link between them remains unclear. Here, we demonstrated the contribution of NOX1 to behavioral repetition induced by repeated stimulation of D2 receptors. Repeated stimulation of D2 receptors upregulated Nox1 mRNA in a striatal subregion-specific manner. The upregulated NOX1 promoted striatal synaptic facilitation in iMSNs by enhancing phosphorylation signaling. These results provide a novel mechanism for D2 receptor-mediated excitatory synaptic facilitation and indicate the therapeutic potential of NOX1 inhibition in compulsivity.

New methods for determination of the keyhole position in the lateral suboccipital approach to avoid transverse-sigmoid sinus injury: Proposition of the groove line as a new surgical landmark

PURPOSE

The asterion is frequently used as an anatomical landmark to determine the location of a keyhole in the lateral suboccipital approach used in craniotomies. However, the asterion may not be ideal because of large individual differences among patients. We examined a simple and safe method for determining an optimal keyhole position (KP) using the digastric groove as a new landmark in the lateral suboccipital approach.

METHODS

Thirty-three patients with trigeminal neuralgia who underwent surgery in our institute between April 2014 and December 2018 were included. The groove line (GL) was designed accurately, extending the digastric groove on the surface of the occipital bone, as the x-axis. The y-axis was depicted from the posterior edge of the digastric groove (the groove point: GP) vertical to the GL. The x-y coordinates represented the distances from GP on each axis. The x-y coordinates of median edge of the transverse-sigmoid sinus (TSJ point), asterion, and the intersection of the GL and transverse sinus (the transverse point: TP) were investigated, based on intraoperative findings and recorded videos.

RESULTS

The x-y coordinated of the TSJ point were (23.9±3.9, 7.2±3.6). In all patients, the TSJ point was located superior to the GL. The x-y coordinates of the asterion were (27.3±6.0, 8.9±4.1), and in 28 of the 33 patients, their coordinates exceeded the TSJ points. The x-coordinate of the TP was 29.5±4.5, and was located behind the TSJ point on the GL in all patients. The shortest distance between the TSJ points and TP was approximately 3mm. According to these measurements, we decided that the optimal KP would be at 20mm from the GP, subjacent to the GL.

CONCLUSIONS

Our methods of using the GL as a new surgical landmark for setting the optimal KP is simple, safe, and useful.

NOX1/NADPH oxidase affects the development of autism-like behaviors in a maternal immune activation model

Autism spectrum disorder (ASD) is a neurodevelopmental disorder caused by genetic and environmental factors. Among the environmental factors, maternal infection is known as one of the principal risk factors for ASD. On the other hand, postmortem studies suggested the relationship of oxidative stress with ASD etiology. However, the role of oxidative stress in the development of ASD remains unclear. Here, we report the involvement of NOX1/NADPH oxidase, an enzyme generating reactive oxygen species (ROS), in behavioral and anatomical abnormalities in a maternal immune activation (MIA) model. In the MIA model of gestational polyinosinic-polycytidylic acid (poly(I:C)) exposure, increased serum levels of IL-6 were observed in both wild-type (WT) and Nox1-deficient mice (Nox1KO). Following the comparable induction of MIA in the two genotypes, impairment of social preference and defects in motor coordination were observed in WT offspring but not in offspring deficient in Nox1. MIA up-regulated NOX1 mRNA in the cerebral cortex and cerebellum of the fetus but not in the adult offspring. Although the development of cortical neurons was unaffected by MIA in either genotype, the dropout of Purkinje cells in lobule VII of MIA-affected offspring was significantly ameliorated in Nox1KO. Taken together, these results suggested that NOX1/NADPH oxidase plays an essential role in some behavioral phenotypes observed in ASD, possibly by promoting the loss of Purkinje cells in the cerebellum.

Effects of Imprinting and Water Activity on Transesterification and Thermostability with Lipases in Ionic Liquid

The effect of bio-imprinting and water activity on catalytic activities and the thermostability of lipases was investigated for transesterification using vinyl acetate and benzyl alcohol as substrates in ionic liquid, [Cnmim][PF6] (n=4,6,8), and benzene. The catalytic activities were enhanced by imprinting in benzene and [C4mim][PF6], and the relations between the transesterification activities and the water activity in both solvents were approximately bell shaped. The reactivity of the transesterification in benzene was higher than that in [C4<br /> mim][PF6]. The effects of water activity and imprinting on the kinetic parameters in [C4mim][PF6] were examined. Without controlling the water content, the values of Km,VA and Km,BA (Michaelis constants of vinyl acetate and benzyl alcohol, respectively) decreased, and the values of Vm (maximum rate) increased by imprinting. On the other hand, by controlling the water content in the organic media, the values of Vm, Km,VA, and Km,BA increased by imprinting. The activities of lipase in ionic liquid are more strongly affected by water activity and imprinting than those in benzene. We observed effects of water activity on thermostability but none from imprinting.

Statins bring the prognostic impact only in peripheral artery disease patients with elevated c-reactive proteins -subanalysis from multicenter registry-

Introduction

Recent trials demonstrated favorable effects of statins on the clinical prognosis, partly through anti-inflammatory properties, in patients with coronary artery disease. However, this favorable effect has not been fully verified in patients with peripheral arterial disease (PAD). We hypothesized that statins exert different prognostic effects depending on the degrees of inflammation at the time of endovascular therapy (EVT).

Methods

This study is a subanalysis from the Toma-Code Registry that is a Japanese prospective cohort of 2,321 consecutive patients with PAD treated by endovascular therapy in hospitals from 2014 to 2016. After the exclusion of patients without information of C-reactive protein (CRP) at the time of index EVT, 2,039 patients including 1,039 statin users and 1,000 statin non-users were ultimately analyzed. The patient enrolled were divided into 4 categories depending on CRP level at the time of EVT; Low-CRP (&lt;0.1 mg/dL), Intermediate-low-CRP (0.1–0.3 mg/dL), Intermediate-High-CRP (0.3–1.0 mg/dL), and High-CRP (&gt;1.0 mg/dL). A composite of death, stroke, myocardial infarction, and major amputation as the primary endpoint of this study was compared between statin users and non-users in each CRP category.

Results

The composite endpoint occurred in 255 patients during the observation period. Overall, statin users had a significantly lower event rate than non-users (Log-rank test: P&lt;0.001). However, there were no significant difference in the event rates between statin users and non-users in the Low-, and Intermediate-Low-CRP categories. Only in the Intermediate-High- and the High-CRP categories, statin users showed a significantly lower event rates than non-users (P=0.02 and P=0.008, respectively, Figures). Additionally, multivariate Cox regression analysis in the High-CRP group revealed that statin use was independently associated with the primary endpoint (adjusted hazard ratio: 0.67 [95% confidence interval: 0.45–0.99]), even after the adjustment of covariants.

Conclusion

Statins may exert a favorable prognostic effect in PAD patients with highly elevated CRP, but not in those with low to moderate CRP level.

Event free survival

Funding Acknowledgement

Type of funding source: None

Transient ischemic attack without self-awareness of symptoms witnessed by bystanders: analysis of the PROMISE-TIA registry

Background and purpose

A transient ischemic attack (TIA) can occur without self‐awareness of symptoms. We aimed to investigate characteristics of patients with a tissue‐based diagnosis of TIA but having no self‐awareness of their symptoms and whose symptoms were witnessed by bystanders.

Methods

We used data from the multicenter registry of 1414 patients with a clinical diagnosis of TIA. For patients without evidence of ischemic lesions on imaging, clinical characteristics were compared between patients with and without self‐awareness of their TIA symptoms.

Results

Among 896 patients (559 men, median age of 70 years), 59 (6.6%) were unaware of their TIA symptoms, but had those symptoms witnessed by bystanders. Patients without self‐awareness of symptoms were older and more frequently female, and more likely to have previous history of stroke, premorbid disability, and atrial fibrillation, but less likely to have dyslipidemia than those with self‐awareness. Patients without self‐awareness of symptoms arrive at hospitals earlier than those with self‐awareness (P < 0.001). ABCD² score was higher in patients without self‐awareness of symptoms than those with self‐awareness (median 5 vs. 4, P = 0.002). Having no self‐awareness of symptoms was a significant predictor of ischemic stroke within 1 year after adjustment for sex, ABCD² score, and onset to arrival time (hazard ratio = 2.44, 95% confidential interval: 1.10–4.83), but was not significant after further adjustment for arterial stenosis or occlusion.

Conclusions

Patients with a TIA but having no self‐awareness of their symptoms might have higher risk of subsequent ischemic stroke rather than those with self‐awareness, suggesting urgent management is needed even if patients have no self‐awareness of symptoms.

NOX1/NADPH oxidase in bone marrow-derived cells modulates intestinal barrier function

The involvement of reactive oxygen species (ROS) has been suggested in the development of inflammatory bowel disease (IBD). An impaired intestinal barrier function is common in IBD patients. Here, we report the central role of NOX1/NADPH oxidase, a major source of ROS in nonphagocytic cells, in intestinal barrier dysfunction. By in vivo imaging using L-012 as a probe, a time-dependent increase in ROS was demonstrated in the abdomen of wild-type mice (WT) administered lipopolysaccharide (LPS: 6 mg/kg i.p.), but it was almost completely abolished in mice deficient in Nox1 (Nox1-KO) or the inducible nitric oxide synthase gene (iNOS-KO). By ex vivo imaging, increased ROS production was mainly shown in the ileum, where enhanced immunostaining of NOX1 was observed on the apical side of the epithelium. On the other hand, a punctate staining pattern of 3-nitrotyrosine, a marker of peroxynitrite production, was demonstrated in the lamina propria. When LPS-induced intestinal hyperpermeability was assessed by the oral administration of fluorescein isothiocyanate-conjugated dextran (FD-4), it was significantly suppressed in Nox1-KO as well as iNOS-KO. When Nox1-KO adoptively transferred with WT bone marrow were treated with LPS, the serum level of FD-4 was significantly elevated, whereas it remained unchanged in WT receiving bone marrow derived from Nox1-KO. Concomitantly, the activation of matrix metalloproteinase-9 induced by LPS was alleviated not only in intestinal tissue but also in peritoneal macrophages of Nox1-KO. Up-regulation of iNOS by LPS was significantly inhibited in macrophages deficient in Nox1, illustrating a functional hierarchy in NOX1/iNOS signaling. Together, these findings suggest that NOX1 in bone marrow-derived cells, but not epithelial cells, perturbs intestinal barrier integrity during endotoxemia.

Enzymatic Kinetics of Solvent-free Esterification with Bio-imprinted Lipase

To avoid the use of compounds that burden the environment, a solvent-free enzymatic<br /> reaction was the focus of this study. Investigated were the catalytic activities and kinetics of lipases that were pretreated with carboxylic acids for the solvent-free esterification of propionic acid with isoamyl alcohol. The enhancements of the esterification yields and rates by the bio-imprinting effects of carboxylic acids were observed. We found no inhibition of isoamyl alcohol on the solvent-free enzymatic esterification, and obtained a large imprinting effect under a largely excessive amount of isoamyl alcohol to propionic acid. From the kinetic analysis, the imprinting of lipases mainly enhanced the catalytic reaction rate constant rather than the affinity between lipase and propionic acid compared with untreated lipase. The bio-imprinting treatment of lipase is found to be very effective for the yield and kinetics in solvent-free esterification.

Influence of the trapeziometacarpal joint fusion on thumb muscles and thumb-tip movement: A cadaveric study

BACKGROUND

Trapeziometacarpal (TMC) arthrodesis provides stability and strength of the thumb, whereas fixation of the TMC joint restricts motion of the thumb, which may consequently impair the activity of daily living. The objective of our study was to investigate how length and area of the thumb-tip trajectory were reduced after the TMC joint fusion.

METHODS

Six fresh, frozen cadavers were used for this study. Tension was applied to the distal tendons of 4 extrinsic thumb muscles (extensor pollicis longus, flexor pollicis longus, abductor pollicis longus, and extensor pollicis brevis) by servomotor, whereas tension was applied to 4 intrinsic muscles (abductor pollicis brevis, opponens pollicis, flexor pollicis brevis, and adductor pollicis) using static weights. The thumb-tip trajectory was examined using a motion capture system without tension and with 5 different weights to induce intrinsic muscle tension before and after the TMC joint fusion.

FINDINGS

When tension was applied to the intrinsic muscles, the length of the thumb-tip trajectory decreased in all conditions compared with that before the TMC joint fusion, whereas the trajectory decreased only when the abductor pollicis longus was pulled. The overall thumb-tip trajectory area was reduced to approximately 30% compared with that before the TMC joint fusion.

INTERPRETATION

Thumb-tip trajectory was restricted by the TMC joint fusion to approximately 30%. However, the reduced area was found tolerable for performing daily activities. Thus, arthrodesis can be the first-line treatment in patients who wish to engage in activities of daily living without difficulties.

Abstract P3-03-35: Prevalence and risk factors associated with development of lymphedema after axillary lymph node dissection among breast cancer patients: Single center retrospective study

Background: Lymphedema in breast cancer is one of the most important complications, and causes symptoms of arm swelling, heaviness and limited movement. Once lymphedema has occurred, it is difficult to cure. Nowadays, treatment with axillary lymph node dissection (ALND) has been decreasing among breast cancer patients as a result of the ACOSOG Z0011, AMAROS and IBCSG 23-01 trials. However, some cases require ALND for ALN metastasis. ALND increases the risk of lymphedema and detracts from quality of life, but the surgical procedure based on anatomical landmarks has not been changed for several decades. The upper borderline for ALND might cause injury to lymph ducts from arms, and incidence and risk factors for lymphedema after ALND are still unclear. Our aim was to identify prevalence and risk factors associated with development of lymphedema after ALND among breast cancer patients.

Methods: This retrospective study was based on data collected from 178 breast cancer patients who underwent ALND in Nagasaki University Hospital, Japan, between 2005 and 2017. Lymphedema was defined as symptomatic arm swelling with &gt;2 cm difference in circumference of the arm compared with that of the contralateral arm. We classified the patients with and without lymphedema, and compared them regarding surgical and pathological findings. Univariate and multivariate analyses were performed to evaluate the risk factors, using the χ2 test, Student's t-test and Cox logistic regression analysis.

Results: Prevalence of lymphedema was 16% (28/178 patients) and mean time interval from surgery to development of lymphedema was 463 days. In univariate analysis, there was a significant difference in postmastectomy radiation therapy (PMRT) (p = 0.02) and the number of patients with &gt;18 dissected ALNs (p = 0.02). Body mass index (p = 0.6), administration of docetaxel (p = 0.2), and smoking (p = 0.07) did not significantly increase lymphedema. In multivariate analysis, PMRT (p = 0.01) and dissection of &gt;18 ALNs (p = 0.001) significantly increased the risk of lymphedema, whereas smoking did not (p = 0.4).

Conclusion: Our study suggested that PMRT and number of dissected ALNs were risk factors for lymphedema. Aggressive and empiric ALND might be associated with axillary lymph duct damage. Therefore, we plan to introduce axillary reverse mapping using indocyanine green to reduce the risk of lymphedema in breast cancer patients who undergo ALND.

Citation Format: Hara Y, Otsubo R, Inamasu E, Matsumoto M, Yano H, Sakimura C, Kuba S, Yamanouchi K, Eguchi S, Nagayasu T. Prevalence and risk factors associated with development of lymphedema after axillary lymph node dissection among breast cancer patients: Single center retrospective study [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-03-35.

Curve Effect on Singlet Diradical Contribution in Kekulé-type Diradicals: A Sensitive Probe for Quinoidal Structure in Curved π-Conjugated Molecules

Curved (non-planar) aromatic compounds have attracted significant research attention in the fields of basic chemistry and materials science. The contribution of the quinoidal structure in the curved π-conjugated structures has been proposed to be the key for materials functions. In this study, the curve effect on the quinoidal contribution was investigated in Kekulé-type singlet diradicals (S-DR1-4) as a sensitive probe for quinoidal structures in curved π-conjugated molecules. The quinoidal contribution in S-DR1-4 was found to increase with increasing the curvature of the curved structure, which was quantitatively analyzed using NBO analysis and the natural orbital occupation numbers computed by the CASSCF method. The curve effect on the singlet-triplet energy gap was examined by the CASPT2 method. The singlet-triplet energy gaps for the highly π-conjugated diradicals were determined for the first time using the CASPT2 method. Substantial quinoidal contribution was found in the curved structures of the delocalized singlet diradicals S-DR1-4, in contrast to its absence in the corresponding triplet states T-DR1-4.

Extraction Mechanism of Ferric and Manganese Ions with Aqueous Two-phase System Formed by Ionic Liquid and Polyethylene Glycol

In this work, we employed an aqueous two-phase system formed by an ionic liquid and polyethylene glycol for the separation of Fe(III), which is the most commonly used metal in the world, and Mn(II), which is currently used in many industries. We found that the extraction mechanisms of Fe(III) and Mn(II) were strongly influenced by the concentration of the hydrochloric acid that dissolved the metal salt. The ion pair reaction was the predominant mechanism that generated the Fe(III) and Mn(II) extractions. At a lower concentration of hydrochloric acid, metal ions were extracted because of the reaction between a metal cation and a dodecylsulfonate anion. At a higher concentration of hydrochloric acid, the reaction between a metal chlorocomplex anion and a hexylmethylimidazolium cation also proceeded. The aqueous two-phase system, composed of ionic liquid and polyethylene glycol, is promising for metal separation based on the difference in the affinity of metal with alkyl-sulfonate in a low HCl concentration and in the stability constant of metal chlorocomplex in a high HCl concentration. The maximum extractability of Fe(III) and Mn(III) was 57.8 and 75.3 %, respectively, with 0.3 mol dm–3 hydrochloric acid concentration.

Thermoelectric properties of dispersant-free semiconducting single-walled carbon nanotubes sorted by a flavin extraction method

Flavin extraction method realized an improved power factor by easy removal of the dispersant from semiconducting SWNT sheet.

[The involvement of NOX1/NADPH oxidase in the development of non-alcoholic steatohepatitis]

Reactive oxygen species (ROS) are known to play a critical role in the development of non-alcoholic steatohepatitis (NASH). To clarify the source of ROS, we examined the expression of superoxide-generating NADPH oxidase isoforms in the liver of high-fat and high-cholesterol (HFC) diet-fed mice. The mRNA expression of NOX1 was significantly elevated in mice on HFC diet for 8 weeks. Increased levels of serum alanine aminotransferase and hepatic cleaved caspase-3 in HFC diet-fed wild-type mice (WT) were significantly ameliorated in mice deficient in Nox1 (Nox1-KO). Increased nitrotyrosine adduct formation, a marker of peroxynitrite-induced injury, was observed in hepatic sinusoids of WT, which was significantly suppressed in NOX1-KO. NOX1 mRNA was mainly expressed in liver sinusoidal endothelial cells (LSECs), and it was significantly up-regulated in primary cultured LSECs treated with palmitic acid (PA). The production of nitric oxide by LSECs and LSECs-dependent relaxation of hepatic stellate cells were significantly attenuated by PA treatment. In contrast, these effects of PA were not observed in cells isolated from Nox1-KO. Taken together, the up-regulation of NOX1 in LSECs may elicit peroxynitrite-mediated cellular injury and impair hepatic microcirculation through reduced bioavailability of nitric oxide. ROS derived from NOX1 may therefore constitute a critical component in the development of NASH.

Cycloartane triterpenoid (23R, 24E)-23-acetoxymangiferonic acid inhibited proliferation and migration in B16-F10 melanoma via MITF downregulation caused by inhibition of both β-catenin and c-Raf-MEK1-ERK signaling axis

We recently reported that (23R, 24E)-23-acetoxymangiferonic acid (23R-AMA), a cycloartane triterpenoid isolated by activity-guided separation from a methanol extract of Garcinia sp. bark, inhibited melanin production via inhibition of tyrosinase (TYR) expression in the B16-F10 melanoma cell line. Since 23R-AMA also inhibited microphthalmia-associated transcription factor (MITF) expression, an upstream factor of TYR, these features of 23R-AMA were thought to be appropriate for development of whitening cosmetics. However, 23R-AMA exhibited growth inhibition other than inhibition of melanin production in B16-F10 cells. Therefore, we investigated biological activities of 23R-AMA in detail, focused on its application as an anti-melanoma compound. In this study, we demonstrated that 23R-AMA inhibited cell proliferation and basic FGF (bFGF)-induced migration in B16-F10 cells. Furthermore, 23R-AMA promoted ser45/thr41 phosphorylation of β-catenin and suppressed its intranuclear accumulation, which was suggested to be related to inhibition of MITF expression. The transcriptional activity of MITF is known to be regulated by phosphorylation via activated ERK. Further investigation revealed that 23R-AMA inhibited phosphorylation of c-Raf, MEK-1, and ERK, and also that of upstream molecules including FAK and c-Src. These results suggested that 23R-AMA inhibited growth and migration of B16-F10 melanoma by regulating both MITF expression and its activity. The activities of 23R-AMA reported in this study are new aspects of cycloartane triterpenoids.

Nicotine and methyl vinyl ketone, major components of cigarette smoke extracts, increase protective amyloid-β peptides in cells harboring amyloid-β precursor protein

The increased ratio of longer amyloid-β (Aβ1-42)/shorter amyloid-β (Aβ1-40) peptides, generated from amyloid precursor protein (APP), is known to promote the development of Alzheimer's disease (AD). To investigate the role of smoking in Aβ production, we determined the production of Aβ species in the presence of nicotine or methyl vinyl ketone (MVK), major components of cigarette smoke extracts, in Flp-In^™ T-REx^™-293 (T-REx293) cells harboring a single copy of human APP. While treatment with nicotine or MVK did not affect the amount of APP, the levels of Aβ1-40 in the culture media were significantly increased. On the other hand, the levels of Aβ1-42 were unaltered by nicotine or MVK treatment. The Aβ1-42/Aβ1-40 ratio was therefore attenuated by cigarette smoke extracts. Similar results were obtained in T-REx293 cells harboring APP of Swedish- or London-type mutation linked to familial AD. T-REx293 cells expressed the nicotinic acetylcholine receptor (nAchR) and tubocurarine, an nAChR antagonist, completely blocked the effects of nicotine. Treatment with nicotine significantly elevated cellular levels of β-secretase that cleaves APP prior to Aβ generation. Taken together, a protective role of nicotine against AD pathology was suggested by enhanced extracellular Aβ1-40 production, which may suppress Aβ fibrillogenesis.

Thromboxane Generation in Patients with Essential Hypertension or Cerebrovascular Disease and Effect of Oral Aspirin

The ability of platelets to synthesize thromboxane B2 (TxB2) from arachidonic acid (AA) or prostaglandin H2 (PGH2) was studied in 26 control subjects, 40 patients with essential hypertension, 20 patients with cerebrovascular disease (CVD) not taking aspirin and 11 patients with CVD taking aspirin. The activity of platelets to form TxB2 from AA or PGH2 was measured using 1 — 14C arachidonic acid or 1—14C PGH2 as a substrate. There was no significant difference in TxB2 generation from AA or PGH2 among the platelets collected from the control subjects, hypertensive patients and CVD patients not taking aspirin.

In CVD patients taking aspirin, marked suppression was observed in TxB2 synthesis from AA, but no suppression in TxB2 synthesis from PGH2. At least 750 mg aspirin per day were required for nearly complete suppression of TxB2 generation from AA.

Cycloartane Triterpenoids with Anti-melanin Deposition Activity

Bioactivity guided separation of the extract of Malaysian Garcinia sp. resulted in the isolation of 23-acetoxy-mangiferonic acid (1) and the absolute configuration of C-23 was elucidated to be R by the advanced Mosher's method. The anti-melanin deposition activity of 1 was caused by the down regulation of tyrosinase gene expression.

Prognostic value of sequencing-based minimal residual disease detection in patients with multiple myeloma who underwent autologous stem-cell transplantation

Background

Most patients with multiple myeloma (MM) are considered to be incurable, and relapse owing to minimal residual disease (MRD) is the main cause of death among these patients. Therefore, new technologies to assess deeper response are required.

Patients and methods

We retrospectively analyzed 125 patients with MM who underwent high-dose melphalan plus autologous stem-cell transplantation (ASCT) to detect MRD in autograft/bone marrow (BM) cells using a next-generation sequencing (NGS)-based method and allele-specific oligonucleotide-polymerase chain reaction (ASO-PCR).

Results

NGS-based method was applicable to 90% and this method had at least one to two logs greater sensitivity compared to ASO-PCR. MRD negative by NGS [MRD^NGS(−)] (defined as <10⁻⁶) in post-ASCT BM cases (n = 26) showed a significantly better progression-free survival (PFS) (96% at 4 years, P < 0.001) and overall survival (OS) (100% at 4 years, P =0.04) than MRD^NGS(+) in post-ASCT BM cases (n = 25). When restricting the analysis to the 39 complete response cases, patients who were MRD^NGS(−) (n = 24) showed a significantly better PFS than those that were MRD^NGS(+) (n = 15) (P =0.02). Moreover, MRD^NGS(−) in post-ASCT BM cases (n = 12) showed significantly a better PFS than MRD^NGS(+) cases (n = 7) where MRD was not detected by ASO-PCR (P = 0.001). Patients whose autografts were negative by NGS-based MRD assessment (<10⁻⁷) (n = 19) had 92% PFS and 100% OS at 4 years post-ASCT. Conversely, the NGS-based MRD positive patients who received post-ASCT treatment using novel agents (n = 49) had a significantly better PFS (P = 0.001) and tended to have a better OS (P= 0.214) than those that were untreated (n = 33).

Conclusions

Low level MRD detected by NGS-based platform but not ASO-PCR has significant prognostic value when assessing either the autograft product or BM cells post-ASCT.

Up-regulation of NOX1/NADPH oxidase following drug-induced myocardial injury promotes cardiac dysfunction and fibrosis

Cardiac fibrosis is a common feature in failing heart and therapeutic strategy to halt the progression of fibrosis is highly needed. We here report on NOX1, a non-phagocytic isoform of superoxide-producing NADPH oxidase, which promotes cardiac fibrosis in a drug-induced myocardial injury model. A single-dose administration of doxorubicin (DOX) elicited cardiac dysfunction accompanied by increased production of reactive oxygen species and marked elevation of NOX1 mRNA in the heart. In mice deficient in Nox1 (Nox1^-/Y), cardiac functions were well retained and overall survival was significantly improved. However, increased level of serum creatine kinase was equivalent to that of wild-type mice (Nox1^+/Y). At 4 days after DOX treatment, severe cardiac fibrosis accompanied by increased hydroxyproline content and activation of matrix metalloproteinase-9 was demonstrated in Nox1^+/Y, but it was significantly attenuated in Nox1^-/Y. When H9c2 cardiomyocytes were exposed to their homogenate, a dose-dependent increase in NOX1 mRNA was observed. Up-regulation of NOX1 mRNA in H9c2 co-incubated with their homogenate was abolished in the presence of TAK242, a TLR4 inhibitor. When isolated cardiac fibroblasts were exposed to H9c2 homogenates, increased proliferation and up-regulation of collagen 3a1 mRNA were demonstrated. These changes were significantly attenuated in cardiac fibroblasts exposed to homogenates from H9c2 harboring disrupted Nox1. These findings suggest that up-regulation of NOX1 following cellular damage promotes cardiac dysfunction and fibrosis by aggravating the pro-fibrotic response of cardiac fibroblasts. Modulation of the NOX1/NADPH oxidase signaling pathway may be a novel therapeutic strategy for preventing heart failure after myocardial injury.