Systemic gene expression profiles according to pain types in individuals with chronic spinal cord injury.

Pain affects most individuals with traumatic spinal cord injury (SCI). Major pain types after SCI are neuropathic or nociceptive, often experienced concurrently. Pain after SCI may be refractory to treatments and negatively affects quality of life. Previously, we analyzed whole blood gene expression in individuals with chronic SCI compared to able-bodied (AB) individuals. Most participants with SCI reported pain (N = 19/28). Here, we examined gene expression of participants with SCI by pain status. Compared to AB, participants with SCI with pain had 468 differentially expressed (DE) genes; participants without pain had 564 DE genes (FDR < 0.05). Among DE genes distinct to participants with SCI with pain, Gene Ontology Biological Process (GOBP) analysis showed upregulated genes were enriched in categories related to T cell activation or inflammation; downregulated genes were enriched in categories related to protein proteolysis and catabolism. Although most participants with pain reported multiple pain types concurrently, we performed a preliminary comparison of gene expression by worst pain problem type. Compared to AB, participants with SCI who ranked neuropathic (N = 9) as worst had one distinct DE gene (TMEM156); participants who ranked nociceptive (N = 10) as worst had 61 distinct DE genes (FDR < 0.05). In the nociceptive group, the GOBP category with the lowest P-value identified among upregulated genes was "positive regulation of T cell activation"; among downregulated genes it was "receptor tyrosine kinase binding". An exploratory comparison of pain groups by principal components analysis also showed that the nociceptive group was enriched in T-cell related genes. A correlation analysis identified genes significantly correlated with pain intensity in the neuropathic or nociceptive groups (N = 145, 65, respectively, Pearson's correlation r > 0.8). While this pilot study highlights challenges of identifying gene expression profiles that correlate with specific types of pain in individuals with SCI, it suggests that T-cell signaling should be further investigated in this context.

Monocyte Subsets and Inflammatory Cytokines in Acute Decompensated Heart Failure.

BACKGROUND: Distinct monocyte subsets predict cardiovascular risk and contribute to heart failure progression in murine models, but they have not been examined in clinical acute decompensated heart failure (ADHF). METHODS AND RESULTS: Blood samples were obtained from 11 healthy control subjects (HCs) and at admission and discharge from 19 ADHF patients. Serologic markers of inflammation were assessed at admission and discharge. Monocyte populations were defined with the use of flow cytometry for cell-surface expression of CD14 and CD16: CD14++CD16- (classic), CD14++CD16+ (intermediate), and CD14+CD16++ (nonclassic). In ADHF patients, C-reactive protein (CRP) and interleukin-6 (IL-6) were higher compared with HCs (both P < .001) and decreased from admission to discharge (CRP: 12.1 ± 10.1 to 8.6 ± 8.4 mg/L [P = .005]; IL-6: 19.8 ± 34.5 to 7.1 ± 4.7 pg/mL [P = .08]). In ADHF patients, the admission proportion of CD14++CD16- monocytes was lower (68% vs 85%; P < .001) and that of CD14++CD16+ (15% vs 8%; P = .002) and CD14+CD16++ (17% vs 7%, P = .07) monocytes higher compared with HCs. Additionally, the proportion of CD14++CD16- monocytes increased (68% to 79%, P = .04) and the CD14+CD16++ monocytes decreased (17% to 7%, P = .049) between admission and discharge. CONCLUSIONS: Following standard treatment of ADHF, the monocyte profile and circulating inflammatory markers shifts to more closely resemble those of HC, suggesting a resolution of the acute inflammatory state. Functional studies are warranted to understand how specific monocyte subsets and systemic inflammation may contribute to ADHF pathophysiology.

The chromatin remodeling protein CHD7, mutated in CHARGE syndrome, is necessary for proper craniofacial and tracheal development.

BACKGROUND: Heterozygous mutations in the chromatin remodeling gene CHD7 cause CHARGE syndrome, a developmental disorder with variable craniofacial dysmorphisms and respiratory difficulties. The molecular etiologies of these malformations are not well understood. Homozygous Chd7 null mice die by E11, whereas Chd7(Gt/+) heterozygous null mice are a viable and excellent model of CHARGE. We explored skeletal phenotypes in Chd7(Gt/+) and Chd7 conditional knockout mice, using Foxg1-Cre to delete Chd7 (Foxg1-CKO) in the developing eye, ear, nose, pharyngeal pouch, forebrain, and gut and Wnt1-Cre (Wnt1-CKO) to delete Chd7 in migrating neural crest cells. RESULTS: Foxg1-CKO mice exhibited postnatal respiratory distress and death, dysplasia of the eye, concha, and frontal bone, hypoplastic maxillary shelves and nasal epithelia, and reduced tracheal rings. Wnt1-CKO mice exhibited frontal and occipital bone dysplasia, hypoplasia of the maxillary shelves and mandible, and cleft palate. In contrast, heterozygous Chd7(Gt/+) mice had apparently normal skeletal development. CONCLUSIONS: Conditional deletion of Chd7 in ectodermal and endodermal derivatives (Foxg1-Cre) or migrating neural crest cells (Wnt1-Cre) results in varied and more severe craniofacial defects than in Chd7(Gt/+) mice. These studies indicate that CHD7 has an important, dosage-dependent role in development of several different craniofacial tissues.

Proposing a Cancer Rehabilitation Medicine Curriculum for Physical Medicine and Rehabilitation Trainees.

ABSTRACT: With the rapid growth and rising interest in the subspecialty of cancer rehabilitation medicine, establishing a structured training and educational curriculum in cancer rehabilitation medicine has become more crucial than ever. For those who are responsible for the educational experiences of students, residents, fellows, or other healthcare professionals, this article provides a systematic approach for establishing a curriculum template relevant for cancer rehabilitation medicine training. This included the assessment of general and targeted needs for learners and educators, rotation goals and objectives, educational strategies, implementation, and evaluation and feedback.

Experiences and recommendations from people with spinal cord injury following participation in a disability education session at an allopathic medical school: a qualitative study.

BACKGROUND: Students in half of US medical schools do not receive formal instruction in providing medical care for people with disabilities. To address this gap in training, our medical school developed several strategies, including a session for second year medical students to address communication skills, knowledge, and attitudes relevant to delivering healthcare for people with disabilities. Here, our objective was to explore perceptions of people with spinal cord injury (SCI) who participated in the session on its content and structure. METHODS: Qualitative research using a focus group of people with SCI who participated in an educational session for medical students in an LCME accredited allopathic US medical school. A purposive sample of adults with SCI (N = 8) participated in a focus group. Data were analyzed using a six-phase thematic analysis. RESULTS: Participants favorably viewed the educational session, felt their participation was valuable, and had suggestions for its improvement. Four major themes were identified: (1) session format, content; (2) addressing student discomfort and avoidance behaviors; (3) increasing student knowledge and preparation; and (4): important lessons from discussions of past and role-played doctor-patient interactions. CONCLUSIONS: First-person input from people with SCI is critical to improve medical education and healthcare provision to the SCI community. To our knowledge, this is the first study to report feedback from stakeholders providing specific recommendations for teaching disabilities awareness to undergraduate medical students. We expect these recommendations to be relevant to the SCI and medical education communities in improving healthcare for people with SCI and other disabilities.

Profiling Immunological Phenotypes in Individuals During the First Year After Traumatic Spinal Cord Injury: A Longitudinal Analysis.

Abstract Individuals with SCI are severely affected by immune system changes, resulting in increased risk of infections and persistent systemic inflammation. While recent data support that immunological changes after SCI differ in the acute and chronic phases of living with SCI, only limited immunological phenotyping in humans is available. To characterize dynamic molecular and cellular immune phenotypes over the first year, we assess RNA (bulk-RNA sequencing), protein, and flow cytometry (FACS) profiles of blood samples from 12 individuals with SCI at 0-3 days and at 3, 6, and 12 months post injury (MPI) compared to 23 uninjured individuals (controls). We identified 967 differentially expressed (DE) genes in individuals with SCI (FDR <0.001) compared to controls. Within the first 6 MPI we detected a reduced expression of NK cell genes, consistent with reduced frequencies of CD56bright, CD56dim NK cells present at 12 MPI. Over 6MPI, we observed increased and prolonged expression of genes associated with inflammation (e.g. HMGB1, Toll-like receptor signaling) and expanded frequencies of monocytes acutely. Canonical T-cell related DE genes (e.g. FOXP3, TCF7, CD4) were upregulated during the first 6 MPI and increased frequencies of activated T cells at 3-12 MPI. Neurological injury severity was reflected in distinct whole blood gene expression profiles at any time after SCI, verifying a persistent 'neurogenic' imprint. Overall, 2876 DE genes emerge when comparing motor complete to motor incomplete SCI (ANOVA, FDR <0.05), including those related to neutrophils, inflammation, and infection. In summary, we identify a dynamic immunological phenotype in humans, including molecular and cellular changes which may provide potential targets to reduce inflammation, improve immunity, or serve as candidate biomarkers of injury severity.

Carbon monoxide induces a late preconditioning-mimetic cardioprotective and antiapoptotic milieu in the myocardium.

A growing body of evidence indicates that carbon monoxide (CO), once perceived merely as a poisonous gas, exerts antiapoptotic and cytoprotective effects. Using a water-soluble CO-releasing molecule (CORM) tricarbonylchloro(glycinato)ruthenium(II) (CORM-3), we previously reported that CO induces a delayed protection against myocardial infarction similar to that observed in the late phase of ischemic preconditioning (PC). In the current study, we investigated the molecular mechanisms underlying this cardioprotective effect. The impact on apoptotic signaling pathways was first examined in the setting of ischemia/reperfusion injury. Mice were pretreated with CORM-3 or iCORM-3 (which does not release CO) and subjected to coronary occlusion/reperfusion 24h later. In mice that received CORM-3, there was a significant reduction in markers of apoptosis (cleaved lamin A, cleaved caspase-3, and cleaved PARP-1) after ischemia/reperfusion injury. To elucidate the mechanism of CORM-3-induced cardioprotection we further examined the activation of transcription factors and induction of cardioprotective and apoptosis modulating proteins. Infusion of CORM-3 rapidly activated the stress-responsive transcription factors nuclear factor kappaB (NF-κB), signal transducers and activators of transcription (STAT)1, STAT3, and NF-E2-related factor-2 (Nrf2). This was followed 24h later by upregulation of cardioprotective proteins (heme oxygenase-1 [HO-1], cyclooxygenase-2 [COX-2], and extracellular superoxide dismutase [Ec-SOD]) and antiapoptotic proteins involving both the mitochondria-mediated (Mcl-1) and the death receptor-mediated (c-FLIP(S) and c-FLIP(L)) apoptosis pathways. We conclude that CO released by CORM-3 triggers a cardioprotective signaling cascade that recruits the transcription factors NF-κB, STAT1/3, and Nrf2 with a subsequent increase in cardioprotective and antiapoptotic molecules in the myocardium leading to the late PC-mimetic infarct-sparing effects. This article is part of a Special Issue entitled 'Possible Editorial'.

Sirtuin 5 levels are limiting in preserving cardiac function and suppressing fibrosis in response to pressure overload.

Heart failure (HF) is the inability of the heart to pump blood sufficiently to meet the metabolic demands of the body. HF with reduced systolic function is characterized by cardiac hypertrophy, ventricular fibrosis and remodeling, and decreased cardiac contractility, leading to cardiac functional impairment and death. Transverse aortic constriction (TAC) is a well-established model for inducing hypertrophy and HF in rodents. Mice globally deficient in sirtuin 5 (SIRT5), a NAD+-dependent deacylase, are hypersensitive to cardiac stress and display increased mortality after TAC. Prior studies assessing SIRT5 functions in the heart have all employed loss-of-function approaches. In this study, we generated SIRT5 overexpressing (SIRT5OE) mice, and evaluated their response to chronic pressure overload using TAC. Compared to littermate controls, SIRT5OE mice were protected against adverse functional consequences of TAC, left ventricular dilation and impaired ejection fraction. Transcriptomic analysis revealed that SIRT5 suppresses key HF sequelae, including the metabolic switch from fatty acid oxidation to glycolysis, immune activation, and fibrotic signaling pathways. We conclude that SIRT5 is a limiting factor in the preservation of cardiac function in response to experimental pressure overload.

A murine model of inducible, cardiac-specific deletion of STAT3: its use to determine the role of STAT3 in the upregulation of cardioprotective proteins by ischemic preconditioning.

Pharmacological studies have shown that signal transducers and activators of transcription (STATs) are necessary for the delayed cardioprotection of ischemic preconditioning (PC). However, pharmacologic STAT inhibitors are not specific; furthermore, the individual role of STAT3 in late PC remains unknown. The objectives of the study were (i) to create an inducible, cardiac-specific STAT3 knockout mouse; (ii) to verify whether STAT3 deletion has any adverse effects in the short term (~1 month); and (iii) to use this novel tool to evaluate the role of STAT3 in the PC-induced upregulation of cardioprotective and anti-apoptotic proteins. We created an inducible, cardiomyocyte-restricted STAT3 deficient mouse (MCM TG:STAT3(flox/flox)) by interbreeding STAT3(flox/flox) mice and tamoxifen-inducible MCM TG mice. Treatment of MCM TG:STAT3(flox/flox) mice with tamoxifen resulted in deletion of STAT3 specifically in cardiac myocytes, concomitant with abrogation of ischemic PC-induced Tyr-705 and Ser-727 phosphorylation of STAT3 and increased STAT3 DNA-binding activity. In vehicle-treated MCM TG:STAT3(flox/flox) mice, ischemic PC increased the expression of cardioprotective (COX-2 and HO-1) and anti-apoptotic (e.g., Mcl-1, Bcl-x(L), c-FLIP(L), c-FLIP(S)) proteins 24h later; in contrast, in tamoxifen-treated MCM TG:STAT3(flox/flox) mice this increase was completely absent. Deletion of STAT3 had no apparent adverse effects on LV structure or function after 35 days. We have developed a novel inducible, cardiomyocyte-restricted STAT3 deficient mouse that can be used to specifically interrogate the role of this transcription factor in cardiovascular pathophysiology in vivo. Our data demonstrate, for the first time, that recruitment of STAT3 plays an obligatory role in the upregulation of cardioprotective and anti-apoptotic proteins and suggest that STAT3 activation is important in inhibiting both the death receptor pathway (which is modulated by c-FLIP(L) and c-FLIP(S)) and the mitochondrial pathway (which is mediated by Mcl-1 and Bcl-x(L)).

Challenges and Lessons Learned for Acute Inpatient Rehabilitation of Persons With COVID-19: Clinical Presentation, Assessment, Needs, and Services Utilization.

OBJECTIVE: The aim of the study was to present: (1) physiatric care delivery amid the SARS-CoV-2 pandemic, (2) challenges, (3) data from the first cohort of post-COVID-19 inpatient rehabilitation facility patients, and (4) lessons learned by a research consortium of New York and New Jersey rehabilitation institutions. DESIGN: For this clinical descriptive retrospective study, data were extracted from post-COVID-19 patient records treated at a research consortium of New York and New Jersey rehabilitation inpatient rehabilitation facilities (May 1-June 30, 2020) to characterize admission criteria, physical space, precautions, bed numbers, staffing, employee wellness, leadership, and family communication. For comparison, data from the Uniform Data System and eRehabData databases were analyzed. The research consortium of New York and New Jersey rehabilitation members discussed experiences and lessons learned. RESULTS: The COVID-19 patients (N = 320) were treated during the study period. Most patients were male, average age of 61.9 yrs, and 40.9% were White. The average acute care length of stay before inpatient rehabilitation facility admission was 24.5 days; mean length of stay at inpatient rehabilitation facilities was 15.2 days. The rehabilitation research consortium of New York and New Jersey rehabilitation institutions reported a greater proportion of COVID-19 patients discharged to home compared with prepandemic data. Some institutions reported higher changes in functional scores during rehabilitation admission, compared with prepandemic data. CONCLUSIONS: The COVID-19 pandemic acutely affected patient care and overall institutional operations. The research consortium of New York and New Jersey rehabilitation institutions responded dynamically to bed expansions/contractions, staff deployment, and innovations that facilitated safe and effective patient care.

The beneficial effects of postinfarct cytokine combination therapy are sustained during long-term follow-up.

We have previously reported that administration of granulocyte colony-stimulating factor (G-CSF)+Flt-3 ligand (FL) or G-CSF+stem cell factor (SCF) improves left ventricular (LV) function and halts LV remodeling at 35 d after myocardial infarction (MI). In the current study, we investigated whether these beneficial effects are sustained in the long term - an issue of fundamental importance for clinical translation. Mice undergoing a 30-min coronary occlusion followed by reperfusion received vehicle (group I), G-CSF+FL (group II), G-CSF+SCF (group III), or G-CSF alone (group IV) starting 4 h after reperfusion and were euthanized 48 wk later. LV structure and function were assessed by serial echocardiography before and at 48 h and 4, 8, 16, 32, and 48 wk after MI. During follow-up, mice in group I exhibited worsening of LV function and progressive LV remodeling. Compared with group I, both groups II and III exhibited improved LV EF at 4 wk after MI; however, only in group II was this improvement sustained at 48 wk. Group II was also the only group in which the decrease in infarct wall thickening fraction, the LV dilatation, and the increase in LV mass were attenuated vs. group I. We conclude that the beneficial effect of G-CSF+FL on postinfarction LV dysfunction and remodeling is sustained for at least 11 months, and thus is likely to be permanent. In contrast, the effect of G-CSF+SCF was not sustained beyond the first few weeks, and G-CSF alone is ineffective. To our knowledge, this is the first long-term study of cytokines in postinfarction LV remodeling. The results reveal heretofore unknown differential actions of cytokines and have important translational implications.

Postinfarct cytokine therapy regenerates cardiac tissue and improves left ventricular function.

We systematically investigated the comparative efficacy of three different cytokine regimens, administered after a reperfused myocardial infarction, in regenerating cardiac tissue and improving left ventricular (LV) function. Wild-type (WT) mice underwent a 30-minute coronary occlusion followed by reperfusion and received vehicle, granulocyte colony-stimulating factor (G-CSF)+Flt-3 ligand (FL), G-CSF+stem cell factor (SCF), or G-CSF alone starting 4 hours after reperfusion. In separate experiments, chimeric mice generated by reconstitution of radioablated WT mice with bone marrow from enhanced green fluorescent protein (EGFP) transgenic mice underwent identical protocols. Mice were euthanized 5 weeks later. Echocardiographically, LV function was improved in G-CSF+FL- and G-CSF+SCF-treated but not in G-CSF-treated mice, whereas LV end-diastolic dimensions were smaller in all three groups. Morphometrically, cytokine-treated hearts had smaller LV diameter and volume. Numerous EGFP-positive cardiomyocytes, capillaries, and arterioles were noted in the infarcted region in cytokine-treated chimeric mice treated with G-CSF+FL or G-CSF+SCF, but the numbers were much smaller in G-CSF-treated mice. G-CSF+FL therapy mobilized bone marrow-derived cells exhibiting increased expression of surface antigens (CD62L and CD11a) that facilitate homing. We conclude that postinfarct cytokine therapy with G-CSF+FL or G-CSF+SCF limits adverse LV remodeling and improves LV performance by promoting cardiac regeneration and probably also by exerting other beneficial actions unrelated to regeneration, and that G-CSF alone is less effective.

Reliability of the Bryce/Ragnarsson spinal cord injury pain taxonomy.

BACKGROUND/OBJECTIVE: Pain is a common secondary complication of spinal cord injury (SCI). However, the literature offers varying estimates of the numbers of persons with SCI who develop pain. The variability in these numbers is caused in part by differences in the classification of pain; there is currently no commonly accepted classification system for pain affecting persons after SCI. This study investigated the interrater reliability of the Bryce/Ragnarsson SCI pain taxonomy (BR-SCI-PT). The hypothesis was that, when used by physicians with minimal training in the BR-SCI-PT, it would have high interrater reliability for the categorization of reported pains. METHODS: One hundred thirty-five vignettes, each of which described a person with SCI with one or more different etiologic subtypes of pain, were evaluated by 5 groups of up to 10 physicians with SCI subspecialization (39 respondents total). Physician classifications were compared with those made by the investigators. RESULTS: Of 179 pain descriptions, 83% were categorized correctly to one of the 15 BR-SCI-PT pain types; 93% were categorized correctly with respect to level (above/at/below neurological level of injury), whereas 90% were categorized correctly as being either nociceptive or neuropathic. Subjects expressed a generally high confidence in the correctness of their classifications. CONCLUSIONS: Substantial interrater agreement was achieved in determining subtypes of pain within the BR-SCI-PT. The agreement was improved for categorizing within less restrictive categories (ie, with respect to the neurological level of injury and whether the pain was nociceptive or neuropathic).

Aging with spinal cord injury.

The years after SCI may be associated with acceleration of the aging process because of diminished physiologic reserves and increased demands on functioning body systems. Clinicians with expertise in the treatment and prevention of SCI-specific secondary complications need to collaborate with gerontologists and primary care specialists and need to invest in the training of future physicians to ensure a continuum of accessible, cost-effective, and high-quality care that meets the changing needs of the SCI population. Managed care payers often do not adequately cover long-term disability needs to prevent secondary SCI-specific complications. In this era of increasing accountability, evidence-based clinical practice guidelines are needed to document scientific evidence and professional consensus to effectively diagnose, treat, and manage clinical conditions; to reduce unnecessary testing and procedures; and to improve patient outcomes. Longitudinal research is needed to minimize cohort effects that contribute to misinterpretation of cross-sectional findings as representative of long-term changes in health and functioning. However, longitudinal studies confound chronologic age, time since injury, and environmental change. Thus, time-sequential research, which controls for such confounding effects, is essential, as is research on the effects of gender,culture, and ethnicity. If we consider how much progress has been made over the past 50 years with respect to SCI mortality related to infectious disease, we can expect to achieve even greater progress against the effects of aging in the next 50 years. Recent developments in molecular biology regarding growth and neuro-trophic factors are bringing us closer to the goal of repairing the damaged spinal cord. The challenge remains for rehabilitation professionals to provide the most comprehensive and holistic approach to long-term follow-up, with an emphasis on health promotion and disease prevention, to postpone functional decline and enhance QOL.

IL-6 plays an obligatory role in late preconditioning via JAK-STAT signaling and upregulation of iNOS and COX-2.

OBJECTIVE: We sought to determine whether interleukin (IL)-6 modulates myocardial infarction or the late phase of preconditioning (PC). METHODS: Wild-type and IL-6(-/-) mice underwent a 30-min coronary occlusion followed by 24 h of reperfusion with or without six cycles of coronary occlusion/reperfusion 24 h earlier. Myocardial IL-6 protein expression, activation of Janus kinase (JAK) 1 and JAK2, and signal transducers and activators of transcription (STAT) 1 and STAT3 after ischemic PC protocol were examined. The expression of the inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 was determined 24 h after the PC ischemia. RESULTS: In preconditioned wild-type mice, infarct size was reduced from 60.5+/-2.6% of the risk region to 33.5+/-3.6%, indicating a late PC effect. In nonpreconditioned IL-6(-/-) mice, infarct size was similar to that observed in wild-type mice (59.9+/-3.8%), indicating that the deletion of IL-6 has no effect on infarct size. However, in preconditioned IL-6(-/-) mice, infarct size was not reduced (65.1+/-3.1%), indicating that the infarct-sparing effect was completely abrogated. Ischemic PC increased the expression of IL-6 in the cytoplasm of cardiomyocytes in the ischemic/reperfused zone. In IL-6(-/-) mice, the ischemic PC-induced activation of JAK1 and JAK2 and STAT1 and STAT3 was significantly reduced, and the increase in iNOS and COX-2 protein expression 24 h after the PC ischemia was markedly attenuated. CONCLUSION: IL-6 does not modulate myocardial infarct size in naïve myocardium. However, following a PC stimulus, IL-6 is obligatorily required for the activation of the JAK-STAT pathway, the ensuing upregulation of iNOS and COX-2 (co-mediators of late PC), and the development of a cardioprotective phenotype.

Design and Evaluation of Tumor-Specific Dendrimer Epigenetic Therapeutics.

Histone deacetylase inhibitors (HDACi) are promising therapeutics for cancer. HDACi alter the epigenetic state of tumors and provide a unique approach to treat cancer. Although studies with HDACi have shown promise in some cancers, variable efficacy and off-target effects have limited their use. To overcome some of the challenges of traditional HDACi, we sought to use a tumor-specific dendrimer scaffold to deliver HDACi directly to cancer cells. Here we report the design and evaluation of tumor-specific dendrimer-HDACi conjugates. The HDACi was conjugated to the dendrimer using an ester linkage through its hydroxamic acid group, inactivating the HDACi until it is released from the dendrimer. Using a cancer cell model, we demonstrate the functionality of the tumor-specific dendrimer-HDACi conjugates. Furthermore, we demonstrate that unlike traditional HDACi, dendrimer-HDACi conjugates do not affect tumor-associated macrophages, a recently recognized mechanism through which drug resistance emerges. We anticipate that this new class of cell-specific epigenetic therapeutics will have tremendous potential in the treatment of cancer.

The PTIP-Associated Histone Methyltransferase Complex Prevents Stress-Induced Maladaptive Cardiac Remodeling.

Pressure overload induces stress-induced signaling pathways and a coordinated transcriptional response that begets concentric cardiac hypertrophy. Although concentric hypertrophy initially attenuates wall stress and maintains cardiac function, continued stress can result in maladaptive cardiac remodeling. Cardiac remodeling is orchestrated by transcription factors that act within the context of an epigenetic landscape. Since the epigenetic landscape serves as a molecular link between environmental factors (stress) and cellular phenotype (disease), defining the role of the epigenome in the development and progression of cardiac remodeling could lead to new therapeutic approaches. In this study, we hypothesized that the epigenetic landscape is important in the development of cardiac hypertrophy and the progression to maladaptive remodeling. To demonstrate the importance of the epigenome in HF, we targeted the PTIP-associated histone methyltransferase complex in adult cardiac myocytes. This complex imparts histone H3 lysine 4 (H3K4) methylation marks at actively expressed genes. We subjected PTIP null (PTIP-) mice to 2 weeks of transverse aortic constriction, a stress that induces concentric hypertrophy in control mice (PTIP+). PTIP- mice have a maladaptive response to 2wk of transverse aortic constriction (TAC)-induced pressure overload characterized by cardiac dilatation, decreased LV function, cardiac fibrosis, and increased cell death. PTIP deletion resulted in altered stress-induced gene expression profiles including blunted expression of ADRA1A, ADRA1B, JUN, ATP2A2, ATP1A2, SCN4B, and CACNA1G. These results suggest that H3K4 methylation patterns and the complexes that regulate them, specifically the PTIP-associated HMT, are necessary for the adaptive response to TAC.

Delayed adaptation of the heart to stress: late preconditioning.

The early phase of preconditioning (PC) lasts 2 to 3 hours and protects against myocardial infarction, but not against stunning. In contrast, the late phase of PC lasts for 3 to 4 days and protects against both myocardial stunning and infarction, making this phenomenon more clinically relevant. Late PC is a genetic reprogramming of the heart that involves the activation of several stress-responsive genes, which ultimately results in the development of a cardioprotective phenotype. Sublethal ischemic insults release chemical signals (nitric oxide [NO], adenosine, and reactive oxygen species) that trigger a series of signaling events (eg, activation of protein kinase C, Src protein tyrosine kinases, Janus kinases 1/2, and nuclear factor-kappaB) and culminates in increased synthesis of inducible NO synthase, cyclooxygenase-2, heme oxygenase-1, aldose reductase, Mn superoxide dismutase, and probably other cardioprotective proteins. In addition to ischemia, heat stress, exercise, and cytokines can also induce a similar series of events. Perhaps most importantly, many pharmacologic agents (eg, NO donors, adenosine receptor agonists, endotoxin derivatives, or opioid receptor agonists) can mimic the effects of ischemia in inducing the late phase of PC, suggesting that this phenomenon might be exploited therapeutically. The purpose of this review is to summarize the mechanisms that underlie the late phase of ischemic PC.

Loss of H3K4 methylation destabilizes gene expression patterns and physiological functions in adult murine cardiomyocytes.

Histone H3 lysine 4 (H3K4me) methyltransferases and their cofactors are essential for embryonic development and the establishment of gene expression patterns in a cell-specific and heritable manner. However, the importance of such epigenetic marks in maintaining gene expression in adults and in initiating human disease is unclear. Here, we addressed this question using a mouse model in which we could inducibly ablate PAX interacting (with transcription-activation domain) protein 1 (PTIP), a key component of the H3K4me complex, in cardiac cells. Reducing H3K4me3 marks in differentiated cardiomyocytes was sufficient to alter gene expression profiles. One gene regulated by H3K4me3 was Kv channel-interacting protein 2 (Kcnip2), which regulates a cardiac repolarization current that is downregulated in heart failure and functions in arrhythmogenesis. This regulation led to a decreased sodium current and action potential upstroke velocity and significantly prolonged action potential duration (APD). The prolonged APD augmented intracellular calcium and in vivo systolic heart function. Treatment with isoproterenol and caffeine in this mouse model resulted in the generation of premature ventricular beats, a harbinger of lethal ventricular arrhythmias. These results suggest that the maintenance of H3K4me3 marks is necessary for the stability of a transcriptional program in differentiated cells and point to an essential function for H3K4me3 epigenetic marks in cellular homeostasis.