Loss of Mir146b with aging contributes to inflammation and mitochondrial dysfunction in thioglycollate-elicited peritoneal macrophages

Macrophages undergo programmatic changes with age, leading to altered cytokine polarization and immune dysfunction, shifting these critical immune cells from protective sentinels to disease promoters. The molecular mechanisms underlying macrophage inflammaging are poorly understood. Using an unbiased RNA sequencing (RNA-seq) approach, we identified Mir146b as a microRNA whose expression progressively and unidirectionally declined with age in thioglycollate-elicited murine macrophages. Mir146b deficiency led to altered macrophage cytokine expression and reduced mitochondrial metabolic activity, two hallmarks of cellular aging. Single-cell RNA-seq identified patterns of altered inflammation and interferon gamma signaling in Mir146b-deficient macrophages. Identification of Mir146b as a potential regulator of macrophage aging provides novel insights into immune dysfunction associated with aging.

SARM1 depletion rescues NMNAT1-dependent photoreceptor cell death and retinal degeneration

Leber congenital amaurosis type nine is an autosomal recessive retinopathy caused by mutations of the NAD+ synthesis enzyme NMNAT1. Despite the ubiquitous expression of NMNAT1, patients do not manifest pathologies other than retinal degeneration. Here we demonstrate that widespread NMNAT1 depletion in adult mice mirrors the human pathology, with selective loss of photoreceptors highlighting the exquisite vulnerability of these cells to NMNAT1 loss. Conditional deletion demonstrates that NMNAT1 is required within the photoreceptor. Mechanistically, loss of NMNAT1 activates the NADase SARM1, the central executioner of axon degeneration, to trigger photoreceptor death and vision loss. Hence, the essential function of NMNAT1 in photoreceptors is to inhibit SARM1, highlighting an unexpected shared mechanism between axonal degeneration and photoreceptor neurodegeneration. These results define a novel SARM1-dependent photoreceptor cell death pathway and identifies SARM1 as a therapeutic candidate for retinopathies.

Impaired monocyte cholesterol clearance initiates age-related retinal degeneration and vision loss

Advanced age-related macular degeneration (AMD), the leading cause of blindness among people over 50 years of age, is characterized by atrophic neurodegeneration or pathologic angiogenesis. Early AMD is characterized by extracellular cholesterol-rich deposits underneath the retinal pigment epithelium (RPE) called drusen or in the subretinal space called subretinal drusenoid deposits (SDD) that drive disease progression. However, mechanisms of drusen and SDD biogenesis remain poorly understood. Although human AMD is characterized by abnormalities in cholesterol homeostasis and shares phenotypic features with atherosclerosis, it is unclear whether systemic immunity or local tissue metabolism regulates this homeostasis. Here, we demonstrate that targeted deletion of macrophage cholesterol ABC transporters A1 (ABCA1) and -G1 (ABCG1) leads to age-associated extracellular cholesterol-rich deposits underneath the neurosensory retina similar to SDD seen in early human AMD. These mice also develop impaired dark adaptation, a cardinal feature of RPE cell dysfunction seen in human AMD patients even before central vision is affected. Subretinal deposits in these mice progressively worsen with age, with concomitant accumulation of cholesterol metabolites including several oxysterols and cholesterol esters causing lipotoxicity that manifests as photoreceptor dysfunction and neurodegeneration. These findings suggest that impaired macrophage cholesterol transport initiates several key elements of early human AMD, demonstrating the importance of systemic immunity and aging in promoting disease manifestation. Polymorphisms in genes involved with cholesterol transport and homeostasis are associated with a significantly higher risk of developing AMD, thus making these studies translationally relevant by identifying potential targets for therapy.

Disrupted cholesterol metabolism promotes age-related photoreceptor neurodegeneration

Photoreceptors have high intrinsic metabolic demand and are exquisitely sensitive to metabolic perturbation. In addition, they shed a large portion of their outer segment lipid membranes in a circadian manner, increasing the metabolic burden on the outer retina associated with the resynthesis of cell membranes and disposal of the cellular cargo. Here, we demonstrate that deletion of both ABCA1 and ABCG1 in rod photoreceptors leads to age-related accumulation of cholesterol metabolites in the outer retina, photoreceptor dysfunction, degeneration of rod outer segments, and ultimately blindness. A high-fat diet significantly accelerates rod neurodegeneration and vision loss, further highlighting the role of lipid homeostasis in regulating photoreceptor neurodegeneration and vision.

Oxysterol Signatures Distinguish Age-Related Macular Degeneration from Physiologic Aging

Macrophage aging is pathogenic in numerous diseases, including age-related macular degeneration (AMD), a leading cause of blindness in older adults. Although prior studies have explored the functional consequences of macrophage aging, less is known about its cellular basis or what defines the transition from physiologic aging to disease. Here, we show that despite their frequent self-renewal, macrophages from old mice exhibited numerous signs of aging, such as impaired oxidative respiration. Transcriptomic profiling of aged murine macrophages revealed dysregulation of diverse cellular pathways, especially in cholesterol homeostasis, that manifested in altered oxysterol signatures. Although the levels of numerous oxysterols in human peripheral blood mononuclear cells and plasma exhibited age-associated changes, plasma 24-hydroxycholesterol levels were specifically associated with AMD. These novel findings demonstrate that oxysterol levels can discriminate disease from physiologic aging. Furthermore, modulation of cholesterol homeostasis may be a novel strategy for treating age-associated diseases in which macrophage aging is pathogenic.

Macrophage microRNA-150 promotes pathological angiogenesis as seen in age-related macular degeneration

Macrophage aging is pathogenic in diseases of the elderly, including age-related macular degeneration (AMD), a leading cause of blindness in older adults. However, the role of microRNAs, which modulate immune processes, in regulating macrophage dysfunction and thereby promoting age-associated diseases is underexplored. Here, we report that microRNA-150 (miR-150) coordinates transcriptomic changes in aged murine macrophages, especially those associated with aberrant lipid trafficking and metabolism in AMD pathogenesis. Molecular profiling confirmed that aged murine macrophages exhibit dysregulated ceramide and phospholipid profiles compared with young macrophages. Of translational relevance, upregulation of miR-150 in human peripheral blood mononuclear cells was also significantly associated with increased odds of AMD, even after controlling for age. Mechanistically, miR-150 directly targets stearoyl-CoA desaturase-2, which coordinates macrophage-mediated inflammation and pathologic angiogenesis, as seen in AMD, in a VEGF-independent manner. Together, our results implicate miR-150 as pathogenic in AMD and provide potentially novel molecular insights into diseases of aging.

Inflammation-Induced Photoreceptor Cell Death

Neuroinflammation is an important aspect of many diseases of the eye, and experimental animal models have been widely used to determine its impact on retinal homeostasis and neuron survival. Physical separation of the neurosensory retina from the underlying retinal pigment epithelium (RPE) results in activation and infiltration of macrophages. Numerous studies have shown the critical role of macrophages in retinal disease processes. In retinal detachment, accumulation of macrophages in the subretinal space is associated with changes in cytokine and chemokine profile which lead to photoreceptor cell death. Targeted disruption of macrophage chemotaxis significantly reduces retinal detachment-induced photoreceptor degeneration. Apoptosis is the predominant mechanism of cell death; however regulated necrosis is also a contributor of photoreceptor loss. Therefore, effective neuroprotective approaches could integrate combined inhibition of both apoptotic and regulated necrosis pathways.

GDF15 is elevated in mice following retinal ganglion cell death and in glaucoma patients

Glaucoma is the second leading cause of blindness worldwide. Physicians often use surrogate endpoints to monitor the progression of glaucomatous neurodegeneration. These approaches are limited in their ability to quantify disease severity and progression due to inherent subjectivity, unreliability, and limitations of normative databases. Therefore, there is a critical need to identify specific molecular markers that predict or measure glaucomatous neurodegeneration. Here, we demonstrate that growth differentiation factor 15 (GDF15) is associated with retinal ganglion cell death. Gdf15 expression in the retina is specifically increased after acute injury to retinal ganglion cell axons and in a murine chronic glaucoma model. We also demonstrate that the ganglion cell layer may be one of the sources of secreted GDF15 and that GDF15 diffuses to and can be detected in aqueous humor (AH). In validating these findings in human patients with glaucoma, we find not only that GDF15 is increased in AH of patients with primary open angle glaucoma (POAG), but also that elevated GDF15 levels are significantly associated with worse functional outcomes in glaucoma patients, as measured by visual field testing. Thus, GDF15 maybe a reliable metric of glaucomatous neurodegeneration, although further prospective validation studies will be necessary to determine if GDF15 can be used in clinical practice.

Zika Virus Infection in Mice Causes Panuveitis with Shedding of Virus in Tears

Zika virus (ZIKV) is an emerging flavivirus that causes congenital abnormalities and Guillain-Barré syndrome. ZIKV infection also results in severe eye disease characterized by optic neuritis, chorioretinal atrophy, and blindness in newborns and conjunctivitis and uveitis in adults. We evaluated ZIKV infection of the eye by using recently developed mouse models of pathogenesis. ZIKV-inoculated mice developed conjunctivitis, panuveitis, and infection of the cornea, iris, optic nerve, and ganglion and bipolar cells in the retina. This phenotype was independent of the entry receptors Axl or Mertk, given that Axl(-/-), Mertk(-/-), and Axl(-/-)Mertk(-/-) double knockout mice sustained levels of infection similar to those of control animals. We also detected abundant viral RNA in tears, suggesting that virus might be secreted from lacrimal glands or shed from the cornea. This model provides a foundation for studying ZIKV-induced ocular disease, defining mechanisms of viral persistence, and developing therapeutic approaches for viral infections of the eye.

AAV-mediated gene therapy in Dystrophin-Dp71 deficient mouse leads to blood-retinal barrier restoration and oedema reabsorption

Dystrophin-Dp71 being a key membrane cytoskeletal protein, expressed mainly in Müller cells that provide a mechanical link at the Müller cell membrane by direct binding to actin and a transmembrane protein complex. Its absence has been related to blood-retinal barrier (BRB) permeability through delocalization and down-regulation of the AQP4 and Kir4.1 channels (1). We have previously shown that the adeno-associated virus (AAV) variant, ShH10, transduces Müller cells in the Dp71-null mouse retina efficiently and specifically (2,3). Here, we use ShH10 to restore Dp71 expression in Müller cells of Dp71 deficient mouse to study molecular and functional effects of this restoration in an adult mouse displaying retinal permeability. We show that strong and specific expression of exogenous Dp71 in Müller cells leads to correct localization of Dp71 protein restoring all protein interactions in order to re-establish a proper functional BRB and retina homeostasis thus preventing retina from oedema. This study is the basis for the development of new therapeutic strategies in dealing with diseases with BRB breakdown and macular oedema such as diabetic retinopathy (DR).

Telemedicine framework using case-based reasoning with evidences

Telemedicine is the medical practice of information exchanged from one location to another through electronic communications to improve the delivery of health care services. This research article describes a telemedicine framework with knowledge engineering using taxonomic reasoning of ontology modeling and semantic similarity. In addition to being a precious support in the procedure of medical decision-making, this framework can be used to strengthen significant collaborations and traceability that are important for the development of official deployment of telemedicine applications. Adequate mechanisms for information management with traceability of the reasoning process are also essential in the fields of epidemiology and public health. In this paper we enrich the case-based reasoning process by taking into account former evidence-based knowledge. We use the regular four steps approach and implement an additional (iii) step: (i) establish diagnosis, (ii) retrieve treatment, (iii) apply evidence, (iv) adaptation, (v) retain. Each step is performed using tools from knowledge engineering and information processing (natural language processing, ontology, indexation, algorithm, etc.). The case representation is done by the taxonomy component of a medical ontology model. The proposed approach is illustrated with an example from the oncology domain. Medical ontology allows a good and efficient modeling of the patient and his treatment. We are pointing up the role of evidences and specialist's opinions in effectiveness and safety of care.

Dystrophin Dp71 gene deletion induces retinal vascular inflammation and capillary degeneration

We have previously shown that the deletion of the dystrophin Dp71 gene induces a highly permeable blood-retinal barrier (BRB). Given that BRB breakdown is involved in retinal inflammation and the pathophysiology of many blinding eye diseases, here we investigated whether the absence of Dp71 brings out retinal vascular inflammation and vessel loss by using specific Dp71-null mice. The expression of vascular endothelial growth factor (VEGF), quantified by quantitative polymerase chain reaction and enzyme-linked immunosorbent assay methods, was higher in the retina of Dp71-null mice than in wild-type mice. In contrast, no differences were observed in VEGFR-2 and tumor necrosis factor-α expression. Moreover, mRNA expression of water channel, aquaporin 4 (AQP4) was increased after Dp71 deletion. The Dp71 deletion was also associated with the overexpression of intercellular adhesion molecule 1, which is expressed on endothelial cells surface to recruit leukocytes. Consistent with these findings, the total number of adherent leukocytes per retina, assessed after perfusion with fluorescein isothiocyanate-conjugated concanavalin A, was increased in the absence of Dp71. Finally, a significant increase in capillary degeneration quantified after retinal trypsin digestion was observed in mice lacking Dp71. These data illustrate for the first time that the deletion of Dp71 was associated with retinal vascular inflammation, vascular lesions with increased leukocyte adhesion and capillary degeneration. Thus, dystrophin Dp71 could play a critical role in retinal vascular inflammation disease, and therefore represent a potential therapeutic target.

Autophagy supports survival and phototransduction protein levels in rod photoreceptors

Damage and loss of the postmitotic photoreceptors is a leading cause of blindness in many diseases of the eye. Although the mechanisms of photoreceptor death have been extensively studied, few studies have addressed mechanisms that help sustain these non-replicating neurons for the life of an organism. Autophagy is an intracellular pathway where cytoplasmic constituents are delivered to the lysosomal pathway for degradation. It is not only a major pathway activated in response to cellular stress, but is also important for cytoplasmic turnover and to supply the structural and energy needs of cells. We examined the importance of autophagy in photoreceptors by deleting the essential autophagy gene Atg5 specifically in rods. Loss of autophagy led to progressive degeneration of rod photoreceptors beginning at 8 weeks of age such that by 44 weeks few rods remained. Cone photoreceptor numbers were only slightly diminished following rod degeneration but their function was significantly decreased. Rod cell death was apoptotic but was not dependent on daily light exposure or accelerated by intense light. Although the light-regulated translocation of the phototransduction proteins arrestin and transducin were unaffected in rods lacking autophagy, Atg5-deficient rods accumulated transducin-α as they degenerated suggesting autophagy might regulate the level of this protein. This was confirmed when the light-induced decrease in transducin was abolished in Atg5-deficient rods and the inhibition of autophagy in retinal explants cultures prevented its degradation. These results demonstrate that basal autophagy is essential to the long-term health of rod photoreceptors and a critical process for maintaining optimal levels of the phototransduction protein transducin-α. As the lack of autophagy is associated with retinal degeneration and altered phototransduction protein degradation in the absence of harmful gene products, this process may be a viable therapeutic target where rod cell loss is the primary pathologic event.

Seeing through VEGF: innate and adaptive immunity in pathological angiogenesis in the eye

The central role of vascular endothelial growth factor (VEGF) signaling in regulating normal vascular development and pathological angiogenesis has been documented in multiple studies. Ocular anti-VEGF therapy is highly effective for treating a subset of patients with blinding eye disorders such as diabetic retinopathy and neovascular age-related macular degeneration (AMD). However, chronic VEGF suppression can lead to adverse effects associated with poor visual outcomes due to the loss of prosurvival and neurotrophic capacities of VEGF. In this review, we discuss emerging evidence for immune-related mechanisms that regulate ocular angiogenesis in a VEGF-independent manner. These novel molecular and cellular pathways may provide potential therapeutic avenues for a multitarget strategy, preserving the neuroprotective functions of VEGF in those patients whose disease is unresponsive to VEGF neutralization.

Eyeballing cholesterol efflux and macrophage function in disease pathogenesis

Disorders of lipid metabolism are strongly associated with cardiovascular disease. Recently, there has been significant focus on how tissues process lipid deposits. Impaired cholesterol efflux has been shown to be crucial in mediating lipid deposition in atherosclerosis. The inability of macrophages to effectively efflux cholesterol from tissues initiates inflammation, plaque neovascularization, and subsequent rupture. Recent studies suggest that inability to effectively efflux cholesterol from tissues may have global implications far beyond atherosclerosis, extending to the pathophysiology of unrelated diseases. We examine the unifying mechanisms by which impaired cholesterol efflux facilitates tissue-specific inflammation and disease progression in age-related macular degeneration (AMD), a blinding eye disease, and in atherosclerosis, a disease associated with significant cardiovascular morbidity.

Reevaluation of dystrophin localization in the mouse retina

PURPOSE. The roles of dystrophins in retinal physiology remain elusive. The lack of proper clustering of the potassium channel Kir4.1 and of the aquaporin AQP4 was proposed to be the basis of the ERG abnormality observed in many Duchenne muscular dystrophy (DMD) patients. However, the electroretinogram of Dp71-null mice, in which this clustering is disrupted, shows only a moderate reduction of the b-wave with no change in the implicit times. Additionally, the deficit in color discrimination found in DMD patients is hard to explain through the known expression of DMD gene products. The authors thus decided to reexamine their distribution in the mouse retina. METHODS. Messenger RNA distribution was assessed by PCR coupled to laser microdissection of the outer and inner nuclear layers and by in situ hybridization for Dp427. Mouse retinas were double labeled for dystrophins versus presynaptic and postsynaptic proteins or antibodies specific for Dp427 or Dp427+Dp260. RESULTS. Messengers for Dp427, Dp260, and Dp140 were present in the inner nuclear layer. Dp427 mRNA was further detected in bipolar cells and in some amacrine cells by in situ hybridization. Comparative labeling in wild-type and mdx(5Cv) retinas (lacking Dp427) indicated a differential distribution of Dp427 and Dp260 between rod and cone terminals. CONCLUSIONS. In addition to their localization in photoreceptor terminals, Dp427, Dp260, and Dp140 are expressed in inner nuclear layer neurons, notably in bipolar cells for Dp427. Dp427 was proportionally more expressed in cone- than in rod-associated synapses compared with Dp260.

N-acetylcysteine amide (NACA) prevents retinal degeneration by up-regulating reduced glutathione production and reversing lipid peroxidation

Oxidative stress plays a critical role in accelerating retinal pigment epithelial dysfunction and death in degenerative retinal diseases, including age-related macular degeneration. Given the key role of oxidative stress-induced retinal pigment epithelial cell death and secondary photoreceptor loss in the pathogenesis of age-related macular degeneration, we hypothesized that a novel thiol antioxidant, N-acetylcysteine amide (NACA), might ameliorate cellular damage and subsequent loss of vision. Treatment of human retinal pigment epithelial cells with NACA protected against oxidative stress-induced cellular injury and death. NACA acted mechanistically by scavenging existing reactive oxygen species while halting production of reactive oxygen species by reversing lipid peroxidation. Furthermore, NACA functioned by increasing the levels of reduced glutathione and the phase II detoxification enzyme glutathione peroxidase. Treatment of mice exposed to phototoxic doses of light with NACA maintained retinal pigment epithelial cell integrity and prevented outer nuclear layer cell death as examined by histopathologic methods and rescued photoreceptor function as measured by electroretinography. These observations indicate that NACA protects against oxidative stress-induced retinal pigment epithelial and photoreceptor cell death in vitro and in vivo. The data suggest that NACA may be a novel treatment in rescuing retinal function and preventing vision loss secondary to retinal degenerative diseases, including age-related macular degeneration.

Functional implication of Dp71 in osmoregulation and vascular permeability of the retina

Functional alterations of Müller cells, the principal glia of the retina, are an early hallmark of most retina diseases and contribute to their further progression. The molecular mechanisms of these reactive Müller cell alterations, resulting in disturbed retinal homeostasis, remain largely unknown. Here we show that experimental detachment of mouse retina induces mislocation of the inwardly rectifying potassium channels (Kir4.1) and a downregulation of the water channel protein (AQP4) in Müller cells. These alterations are associated with a strong decrease of Dp71, a cytoskeleton protein responsible for the localization and the clustering of Kir4.1 and AQP4. Partial (in detached retinas) or total depletion of Dp71 in Müller cells (in Dp71-null mice) impairs the capability of volume regulation of Müller cells under osmotic stress. The abnormal swelling of Müller cells In Dp71-null mice involves the action of inflammatory mediators. Moreover, we investigated whether the alterations in Müller cells of Dp71-null mice may interfere with their regulatory effect on the blood-retina barrier. In the absence of Dp71, the retinal vascular permeability was increased as compared to the controls. Our results reveal that Dp71 is crucially implicated in the maintenance of potassium homeostasis, in transmembraneous water transport, and in the Müller cell-mediated regulation of retinal vascular permeability. Furthermore, our data provide novel insights into the mechanisms of retinal homeostasis provided by Müller cells under normal and pathological conditions.

[Prevalence and morbidity of G6PD deficiency in sickle cell disease in the homozygote]

Sickle cell disease and G6PD deficiency have similar prevalence of 8 to 10% in Senegalese population. Our objectives were to determine the prevalence of G6PD deficiency in Hb S carriers and normal subjects, and to assess the interaction of G6PD deficiency on clinical severity of sickle cell disease. G6PD activity was measured in 319 sickle cell patients and in 318 subjects without HbS. Clinical severity was compared in male homozygous sickle cell patients (11 with G6PD deficiency and 19 without deficit). In homozygous sickle cell patients, the G6PD status was assessed after correction of reticulocyte count following the micro-centrifugation method of Herz. We found that prevalence of G6PD deficiency was higher in sickle cell disease patients (21.6 %) than in normal subjects (12.3 %) (p = 0.001). No difference was found in the two groups of male sickle cell disease patients concerning number of vaso-occlusive crisis, number of transfusion, frequency of infectious episodes, number of chronic complications, disturbances on patient's activity and total index severity.

Blood transfusion does not have an adverse effect on survival after operation for colorectal cancer

The effect of perioperative blood transfusion on cancer progression remains controversial because retrospective clinical studies have produced conflicting results. We have collected data prospectively on 379 patients undergoing curative surgery for colorectal adenocarcinoma and assessed the effect of variables, including blood transfusion, on survival. Univariate and multivariate survival analysis has been carried out. When the end-point for analysis used was death due to recurrent colorectal carcinoma and non-cancer deaths were censored, there was no difference in cancer-specific survival between transfused and non-transfused patients. Survival analysis was also carried out without censoring the non-cancer deaths and clearly demonstrated how the statistical analysis and data interpretation could be distorted by age-related non-cancer deaths. The incidence of recurrence of colorectal carcinoma was not greater in the transfused group than in the non-transfused group. We conclude that blood transfusion should not be withheld in colorectal surgery for fear of worsening the prognosis.

Adenocarcinoma of the pancreas with osteoclast-like giant cells: a case report with immunocytochemistry

Histological examination of a tumor centered in the body of the pancreas of a 65-year-old Iranian man revealed it to have a substantial component in which osteoclast-like giant cells were set within a stroma of pleomorphic mononuclear cells though other areas were composed of conventional adenocarcinoma. Immunocytochemistry was used to investigate the differentiation of the various component cells of the tumor. The carcinoma cells of the usual type expressed epithelial antigens (EMA and cytokeratin). The giant cells expressed vimentin and showed membrane staining with anti-LCA, in common with examples of cells originating from the mononuclear phagocytic system, including normal osteoclasts. The accompanying stromal cells expressed vimentin only. This implies that the giant cells are likely to have their origin in the bone marrow, whereas the mononuclear stromal cells that separate them may represent tumor cells that have lost their epithelial phenotype. The giant cells are therefore an unusual tissue response to the presence of the carcinoma.

The treatment of recurrent tonsillitis in adults

A prospective study comparing surgical and antibiotic treatment for recurrent tonsillitis in adults suggests that, whilst tonsillectomy is very effective, adequate medical treatment provides an equally good alternative in the majority of patients.