Gene-agnostic approaches to treating inherited retinal degenerations

Most patients with inherited retinal degenerations (IRDs) have been waiting for treatments that are “just around the corner” for decades, with only a handful of seminal breakthroughs happening in recent years. Highlighting the difficulties in the quest for curative therapeutics, Luxturna required 16 years of development before finally obtaining United States Food and Drug Administration (FDA) approval and its international equivalents. IRDs are both genetically and phenotypically heterogeneous. While this diversity offers many opportunities for gene-by-gene precision medicine-based approaches, it also poses a significant challenge. For this reason, alternative (or parallel) strategies to identify more comprehensive, across-the-board therapeutics for the genetically and phenotypically diverse IRD patient population are very appealing. Even when gene-specific approaches may be available and become approved for use, many patients may have reached a disease stage whereby these approaches may no longer be viable. Thus, alternate visual preservation or restoration therapeutic approaches are needed at these stages. In this review, we underscore several gene-agnostic approaches that are being developed as therapeutics for IRDs. From retinal supplementation to stem cell transplantation, optogenetic therapy and retinal prosthetics, these strategies would bypass at least in part the need for treating every individual gene or mutation or provide an invaluable complement to them. By considering the diverse patient population and treatment strategies suited for different stages and patterns of retinal degeneration, gene agnostic approaches are very well poised to impact favorably outcomes and prognosis for IRD patients

Mining the NaV1.7 interactome: Opportunities for chronic pain therapeutics

The peripherally expressed voltage-gated sodium NaV1.7 (gene SCN9A) channel boosts small stimuli to initiate firing of pain-signaling dorsal root ganglia (DRG) neurons and facilitates neurotransmitter release at the first synapse within the spinal cord. Mutations in SCN9A produce distinct human pain syndromes. Widely acknowledged as a "gatekeeper" of pain, NaV1.7 has been the focus of intense investigation but, to date, no NaV1.7-selective drugs have reached the clinic. Elegant crystallographic studies have demonstrated the potential of designing highly potent and selective NaV1.7 compounds but their therapeutic value remains untested. Transcriptional silencing of NaV1.7 by a naturally expressed antisense transcript has been reported in rodents and humans but whether this represents a viable opportunity for designing NaV1.7 therapeutics is currently unknown. The demonstration that loss of NaV1.7 function is associated with upregulation of endogenous opioids and potentiation of mu- and delta-opioid receptor activities, suggests that targeting only NaV1.7 may be insufficient for analgesia. However, the link between opioid-dependent analgesic mechanisms and function of sodium channels and intracellular sodium-dependent signaling remains controversial. Thus, additional new targets - regulators, modulators - are needed. In this context, we mine the literature for the known interactome of NaV1.7 with a focus on protein interactors that affect the channel's trafficking or link it to opioid signaling. As a case study, we present antinociceptive evidence of allosteric regulation of NaV1.7 by the cytosolic collapsin response mediator protein 2 (CRMP2). Throughout discussions of these possible new targets, we offer thoughts on the therapeutic implications of modulating NaV1.7 function in chronic pain

Factors associated with viremia in people living with HIV on antiretroviral therapy in Guatemala

INTRODUCTION: Viral suppression prevents HIV transmission and disease progression, but socio-economic and clinical factors can hinder the goal of suppression. We evaluated factors associated with viral non suppression (VNS) and persistent viremia (PV) in people living with HIV (PLHIV) receiving antiretroviral therapy (ART) in Guatemala. METHODS: We conducted a cross sectional analysis using data from an ongoing cohort of PLHIV attending the largest HIV clinic in Guatemala. Univariable and multivariable analyses were conducted between PLHIV with viral suppression and detectable viremia. VNS was defined as most recent HIV RNA ≥ 200 copies/ml and PV as two consecutive HIV RNA ≥ 200 copies/ml. RESULTS: Of 664 participants, 13.3% had VNS and 7.1% had PV. In univariable analysis disaggregated by gender, low income, poor education, perceived difficulty attending healthcare, and alcohol use were associated with VNS in men while low CD4 at diagnosis, multiple prior ART regimens and treatment interruptions were significant in both genders. Multiple prior ART regimens (adjusted Odds Ratio (aOR) 2.82, [95% confidence interval (CI) 1.59, 4.99], p \u3c 0.01), treatment interruptions (aOR 4.51, [95% CI 2.13, 9.58], p \u3c 0.01), excessive alcohol consumption (aOR 2.56, [95% CI 1.18, 5.54], p \u3c 0.05) perceived difficulty attending healthcare (aOR 2.07, [ 95% CI 1.25, 3.42], p \u3c 0.01) and low CD4 at diagnosis (aOR 2.34, 95% [CI 1.30, 4.20], p \u3c 0.01) were independently associated with VNS on multivariable regression. CONCLUSIONS: We conclude that socio-economic and clinical factors influence viral suppression in our cohort and vary between men and women. Gender specific approaches are necessary to achieve the 90% suppression goal

Medically unexplained symptoms and the problem of power in the primary care consultation: a qualitative study

Background: Patients presenting in primary care frequently exhibit physical symptoms that may be unrelated to organic pathology. Such symptoms are commonly regarded as products of psychological or emotional problems, and their legitimacy as ‘medical’ matters is often called into question. Objectives: Our aim was to explore GPs' attitudes to the management of patients that present with medically unexplained symptoms in primary care. Methods: Semi-structured interviews were conducted with 15 GPs in North-West England. Interviews were audio-taped and subsequently transcribed and analysed using a constant comparison technique. Results: Subjects conceptualized patients presenting with medically unexplained symptoms as the presentation of psychological distress. They presented problems of control and authority in the consultation, and difficulties in managing this had a negative impact on the doctor–patient relationship. Such consultations were frustrating for the GP and potentially harmful to the patient. Conclusion: Patients with medically unexplained symptoms were seen to be presenting with inappropriate symptoms that were a manifestation of emotional or social distress. GPs felt ill-equipped to deal with the presentations and the frustrations they felt and may need help in actively and productively managing these patients

Long-lasting antinociceptive effects of green light in acute and chronic pain in rats

Treatments for chronic pain are inadequate, and new options are needed. Nonpharmaceutical approaches are especially attractive with many potential advantages including safety. Light therapy has been suggested to be beneficial in certain medical conditions such as depression, but this approach remains to be explored for modulation of pain. We investigated the effects of light-emitting diodes (LEDs), in the visible spectrum, on acute sensory thresholds in naive rats as well as in experimental neuropathic pain. Rats receiving green LED light (wavelength 525 nm, 8 h/d) showed significantly increased paw withdrawal latency to a noxious thermal stimulus; this antinociceptive effect persisted for 4 days after termination of last exposure without development of tolerance. No apparent side effects were noted and motor performance was not impaired. Despite LED exposure, opaque contact lenses prevented antinociception. Rats fitted with green contact lenses exposed to room light exhibited antinociception arguing for a role of the visual system. Antinociception was not due to stress/anxiety but likely due to increased enkephalins expression in the spinal cord. Naloxone reversed the antinociception, suggesting involvement of central opioid circuits. Rostral ventromedial medulla inactivation prevented expression of light-induced antinociception suggesting engagement of descending inhibition. Green LED exposure also reversed thermal and mechanical hyperalgesia in rats with spinal nerve ligation. Pharmacological and proteomic profiling of dorsal root ganglion neurons from green LED-exposed rats identified changes in calcium channel activity, including a decrease in the N-type (CaV2.2) channel, a primary analgesic target. Thus, green LED therapy may represent a novel, nonpharmacological approach for managing pain.Career Development Award from the University of Arizona Health Sciences; Children's Tumor Foundation NF1 Synodos grant; start- up seed fund; Young Investigator Award from the Children's Tumor Foundation12 month embargo; Available online 19 November 2016This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Implications of the patient protection and Affordable Care Act on insurance coverage and rehabilitation use among young adult trauma patients

Importance: Trauma is the leading cause of death and disability among young adults, who are also among the most likely to be uninsured. Efforts to increase insurance coverage, including passage of the Patient Protection and Affordable Care Act (ACA), were intended to improve access to care and promote improvements in outcomes. However, despite reported gains in coverage, the ACA\u27s success in promoting use of high-quality care and enacting changes in clinical end points remains unclear.Objectives: To assess for observed changes in insurance coverage and rehabilitation use among young adult trauma patients associated with the ACA, including the Dependent Coverage Provision (DCP) and Medicaid expansion/open enrollment, and to consider possible insurance and rehabilitation differences between DCP-eligible vs -ineligible patients and among stratified demographic and community subgroups.Design, setting, and participants: A longitudinal assessment of DCP implementation and Medicaid expansion/open enrollment using risk-adjusted before-and-after, difference-in-difference, and interrupted time-series analyses was conducted. Eleven years (January 1, 2005, to September 31, 2015) of Maryland Health Services Cost Review Commission data, representing complete patient records from all payers within the state, were used to identify all hospitalized young adult (aged 18-34 years) trauma patients in Maryland during the study period.Results: Of the 69 507 hospitalized patients included, 50 548 (72.7%) were male, and the mean (SD) age was 25 (5) years. Before implementation of the DCP, 1 of 4 patients was uninsured. After ACA implementation, the number fell to less than 1 of 10, with similar patterns emerging in emergency department and outpatient settings. The change was primarily driven by Medicaid expansion/open enrollment, which corresponded to a 20.1 percentage-point increase in Medicaid (95% CI, 18.9-21.3) and an 18.2 percentage-point decrease in uninsured (95% CI, -19.3 to -17.2). No changes were detected among privately insured patients. Rehabilitation use increased by 5.4 percentage points (95% CI, 4.5-6.2)-a 60% relative increase from a baseline of 9%. Mortality (-0.5; 95% CI, -0.9 to -0.1) and failure-to-rescue rates (-4.5; 95% CI, -7.4 to -1.6) also significantly declined. Stratified changes point to significant differences in the percentage of uninsured patients and rehabilitation access across the board, mitigating or even eradicating disparities in certain cases.Conclusions and relevance: For patients who are injured, young, and uninsured, Medicaid expansion/open enrollment in Maryland changed insurance coverage and altered patient outcomes in ways that the DCP alone was never intended to do. Implementation of Medicaid expansion/open enrollment transformed the landscape of trauma coverage, directly affecting the health of one of the country\u27s most vulnerable at-risk groups

Dissecting the role of the CRMP2–neurofibromin complex on pain behaviors

Neurofibromatosis type 1 (NF1), a genetic disorder linked to inactivating mutations or a homozygous deletion of the Nf1 gene, is characterized by tumorigenesis, cognitive dysfunction, seizures, migraine, and pain. Omic studies on human NF1 tissues identified an increase in the expression of collapsin response mediator protein 2 (CRMP2), a cytosolic protein reported to regulate the trafficking and activity of presynaptic N-type voltage-gated calcium (Cav2.2) channels. Because neurofibromin, the protein product of the Nf1 gene, binds to and inhibits CRMP2, the neurofibromin-CRMP2 signaling cascade will likely affect Ca channel activity and regulate nociceptive neurotransmission and in vivo responses to noxious stimulation. Here, we investigated the function of neurofibromin-CRMP2 interaction on Cav2.2. Mapping of >275 peptides between neurofibromin and CRMP2 identified a 15-amino acid CRMP2-derived peptide that, when fused to the tat transduction domain of HIV-1, inhibited Ca influx in dorsal root ganglion neurons. This peptide mimics the negative regulation of CRMP2 activity by neurofibromin. Neurons treated with tat-CRMP2/neurofibromin regulating peptide 1 (t-CNRP1) exhibited a decreased Cav2.2 membrane localization, and uncoupling of neurofibromin-CRMP2 and CRMP2-Cav2.2 interactions. Proteomic analysis of a nanodisc-solubilized membrane protein library identified syntaxin 1A as a novel CRMP2-binding protein whose interaction with CRMP2 was strengthened in neurofibromin-depleted cells and reduced by t-CNRP1. Stimulus-evoked release of calcitonin gene-related peptide from lumbar spinal cord slices was inhibited by t-CNRP1. Intrathecal administration of t-CNRP1 was antinociceptive in experimental models of inflammatory, postsurgical, and neuropathic pain. Our results demonstrate the utility of t-CNRP1 to inhibit CRMP2 protein-protein interactions for the potential treatment of pain

Microglia at sites of atrophy restrict the progression of retinal degeneration via galectin-3 and trem2 interactions

Degenerative diseases of the outer retina, including age-related macular degeneration (AMD), are characterized by atrophy of photoreceptors and retinal pigment epithelium (RPE). In these blinding diseases, macrophages are known to accumulate ectopically at sites of atrophy, but their ontogeny and functional specialization within this atrophic niche remain poorly understood, especially in the human context. Here, we uncovered a transcriptionally unique profile of microglia, marked by galectin-3 upregulation, at atrophic sites in mouse models of retinal degeneration and in human AMD. Using disease models, we found that conditional deletion of galectin-3 in microglia led to defects in phagocytosis and consequent augmented photoreceptor death, RPE damage and vision loss, suggestive of a protective role. Mechanistically, Trem2 signaling orchestrated the migration of microglial cells to sites of atrophy, and there, induced galectin-3 expression. Moreover, pharmacologic Trem2 agonization led to heightened protection, but only in a galectin-3-dependent manner, further signifying the functional interdependence of these two molecules. Likewise in elderly human subjects, we identified a highly conserved population of microglia at the transcriptomic, protein and spatial levels, and this population was enriched in the macular region of postmortem AMD subjects. Collectively, our findings reveal an atrophy-associated specialization of microglia that restricts the progression of retinal degeneration in mice and further suggest that these protective microglia are conserved in AMD