Changes in Mental Health as a Predictor of Cannabis Coping Motives and Consequences: Examining the Impact of COVID-19 Among College Students

Objective: Cannabis use is common among college students and many students use cannabis to cope with negative affect. The COVID-19 pandemic was a particularly stressful time for college students. Subsequently, the present study compared college students who reported increases in anxiety/depression symptoms since COVID-19 stay at home orders to those who reported no change in anxiety/depression symptoms on cannabis coping motives, use frequency, and negative consequences. Specifically, we examined whether self-reported changes (i.e., group that indicated increases) in poor mental health during COVID-19 were associated with problematic cannabis use via higher cannabis coping motives. Method: College students (analytic n = 291) completed an online survey for research credit regarding their personal mental health, COVID-19 stressors, and cannabis use behaviors. Results: Individuals who reported increased depressive symptoms (57.4% of the current sample) due to COVID-19 (as compared to individuals whose depressive symptoms remained the same) reported significantly higher cannabis coping motives (d = .79) as well as more cannabis consequences (d = .37). Further, students who reported increased (61.5% of the current sample) anxiety symptoms (as compared to those whose anxiety symptoms stayed the same) also reported significantly higher cannabis coping motives (d = .47). Moreover, we found that students who reported an increase in depressive/anxiety symptoms reported more cannabis consequences via higher endorsement of cannabis coping motives while controlling for gender, cannabis use frequency, and past-week anxiety/depressive symptoms. Discussion: Providing resources for substance-free coping strategies to manage the mental health impact of COVID-19 may be extremely useful for this population

RPE Tissue-specific Factor H Deletion Induces AMD-like Features

Age-related macular degeneration (AMD) is a central vision-threatening disease, and its development is significantly associated with the Y402H variant in the complement factor H (Cfh) gene. Cfh is a soluble glycoprotein, and a negative regulator of complement activation. It is secreted by retinal pigment epithelium (RPE), liver and immune cells among others, but to date it is unclear whether the origin of the Cfh is of importance in regulating the alternative complement pathway and eye homeostasis. Here, Cfhflx/flx mice were crossed with Best1-cre mice, with the Best1 promoter providing RPE-specific expression of the Cre recombinase, inducing an RPE-specific deletion of loxP flanked Cfh. Cfh(RPE)-/- mice on a mixed C57BL/6 and 129 background exhibited 95% Cre-positive RPE cells in immunostained cryosections. qPCR revealed a concomitant decrease of 95% in Cfh mRNA. Compared to Cfh total knockout mice, Cfh(RPE)-/- animals preserved an intact complement system, with normal levels of circulating Cfh, C3 and Cfb, as well as sub-RPE deposition of the C3-breakdown product iC3b, as also seen in AMD patients. C5b-9 deposition was elevated in cryosections of 6 month old Cfh(RPE)-/- mice, and western blotting analysis of RPE and choroid protein revealed higher Cfh levels compared to controls. F4/80 and CD206 immunostaining revealed sub-RPE accumulation of activated macrophages in 6 month old Cfh(RPE)-/- animals compared to controls. Increased autofluorescence was visualised in 12 month old Cfh(RPE)-/- mice using a micron III, and yellow, drusen-like deposits were evident in fundus imaging relative to wild type and Cre controls. RPE-selective Cfh loss thus manifests in AMD-like changes and may provide insight into the source of secreted Cfh as target for therapeutics

Iron promotes oxidative cell death caused by bisretinoids of retina

Intracellular Fe plays a key role in redox active energy and electron transfer. We sought to understand how Fe levels impact the retina, given that retinal pigment epithelial (RPE) cells are also challenged by accumulations of vitamin A aldehyde adducts (bisretinoid lipofuscin) that photogenerate reactive oxygen species and photodecompose into damaging aldehyde- and dicarbonyl-bearing species. In mice treated with the Fe chelator deferiprone (DFP), intracellular Fe levels, as reflected in transferrin receptor mRNA expression, were reduced. DFP-treated albino Abca4−/− and agouti wild-type mice exhibited elevated bisretinoid levels as measured by high-performance liquid chromatography or noninvasively by quantitative fundus autofluorescence. Thinning of the outer nuclear layer, a parameter indicative of the loss of photoreceptor cell viability, was also reduced in DFP-treated albino Abca4−/−. In contrast to the effects of the Fe chelator, mice burdened with increased intracellular Fe in RPE due to deficiency in the Fe export proteins hephaestin and ceruloplasmin, presented with reduced bisretinoid levels. These findings indicate that intracellular Fe promotes bisretinoid oxidation and degradation. This interpretation was supported by experiments showing that DFP decreased the oxidative/degradation of the bisretinoid A2E in the presence of light and reduced cell death in cell-based experiments. Moreover, light-independent oxidation and degradation of A2E by Fenton chemistry products were evidenced by the consumption of A2E, release of dicarbonyls, and generation of oxidized A2E species in cell-free assays

CD1 Mouse Retina Is Shielded From Iron Overload Caused by a High Iron Diet

Citation: Bhoiwala DL, Song Y, Cwanger A, et al. CD1 mouse retina is shielded from iron overload caused by a high iron diet. Invest Ophthalmol Vis Sci. 2015;56:5344-5352. DOI:10.1167/iovs.15-17026 PURPOSE. High RPE iron levels have been associated with age-related macular degeneration. Mutation of the ferroxidase ceruloplasmin leads to RPE iron accumulation and degeneration in patients with aceruloplasminemia; mice lacking ceruloplasmin and its homolog hephaestin have a similar RPE degeneration. To determine whether a high iron diet (HID) could cause RPE iron accumulation, possibly contributing to RPE oxidative stress in AMD, we tested the effect of dietary iron on mouse RPE iron. METHODS. Male CD1 strain mice were fed either a standard iron diet (SID) or the same diet with extra iron added (HID) for either 3 months or 10 months. Mice were analyzed with immunofluorescence and Perls' histochemical iron stain to assess iron levels. Levels of ferritin, transferrin receptor, and oxidative stress gene mRNAs were measured by quantitative PCR (qPCR) in neural retina (NR) and isolated RPE. Morphology was assessed in plastic sections. RESULTS. Ferritin immunoreactivity demonstrated a modest increase in the RPE in 10-month HID mice. Analysis by qPCR showed changes in mRNA levels of iron-responsive genes, indicating moderately increased iron in the RPE of 10-month HID mice. However, even by age 18 months, there was no Perls' signal in the retina or RPE and no retinal degeneration. CONCLUSIONS. These findings indicate that iron absorbed from the diet can modestly increase the level of iron deposition in the wild-type mouse RPE without causing RPE or retinal degeneration. This suggests regulation of retinal iron uptake at the blood-retinal barriers

Selective Ablation of Megalin in the Retinal Pigment Epithelium Results in Megaophthalmos, Macromelanosome Formation and Severe Retina Degeneration

PURPOSE: Mutations in the megalin-encoding gene, LRP2, cause high myopia as seen in patients suffering from Donnai-Barrow/facio-oculo-acoustico-renal syndrome. Megalin is present in both the nonpigmented epithelium of the ciliary body and in the RPE. In this study, we set out to establish an animal model to study the mechanisms underlying the ocular phenotype and to establish if high myopia/megaophthalmos is induced by postnatal megalin-deficiency in the RPE. METHODS: Postnatal RPE-specific deletion of megalin was generated by crossing mice bearing a homozygous loxP-flanked Lrp2 allele with transgenic mice expressing the Cre recombinase driven by the BEST1 promotor. The model was investigated by immunohistologic techniques, and transmission electron microscopy. RESULTS: Mice with postnatal RPE-specific loss of megalin developed a megaophthalmos phenotype with dramatic increase in ocular size and severe retinal thinning associated with compromised vision. This phenotype was present at postnatal day 14, indicating rapid development in the period from onset of BEST1 promotor activity at postnatal day 10. Additionally, RPE melanosomes exhibited abnormal size and morphology, suggested by electron tomography to be caused by fusion events between multiple melanosomes. CONCLUSIONS: Postnatal loss of megalin in the RPE induces dramatic and rapid ocular growth and retinal degeneration compatible with the high myopia observed in Donnai-Barrow patients. The morphologic changes of RPE melanosomes, believed to be largely inert and fully differentiated at birth, suggested a continued plasticity of mature melanosomes and a requirement for megalin to maintain their number and morphology

Inflammatory adipose activates a nutritional immunity pathway leading to retinal dysfunction.

Age-related macular degeneration (AMD), the leading cause of irreversible blindness among Americans over 50, is characterized by dysfunction and death of retinal pigment epithelial (RPE) cells. The RPE accumulates iron in AMD, and iron overload triggers RPE cell death in vitro and in vivo. However, the mechanism of RPE iron accumulation in AMD is unknown. We show that high-fat-diet-induced obesity, a risk factor for AMD, drives systemic and local inflammatory circuits upregulating interleukin-1β (IL-1β). IL-1β upregulates RPE iron importers and downregulates iron exporters, causing iron accumulation, oxidative stress, and dysfunction. We term this maladaptive, chronic activation of a nutritional immunity pathway the cellular iron sequestration response (CISR). RNA sequencing (RNA-seq) analysis of choroid and retina from human donors revealed that hallmarks of this pathway are present in AMD microglia and macrophages. Together, these data suggest that inflamed adipose tissue, through the CISR, can lead to RPE pathology in AMD

Iron overload and chelation modulates bisretinoid levels in the retina

AimIron dysregulation in conjunction with other disease processes may exacerbate retinal degeneration. We employed models of iron overload and iron chelation to explore the interactions between iron-catalyzed oxidation and photoreactive bisretinoid lipofuscin.MethodsThe mice were injected intravitreally with ferric ammonium citrate (FAC) or were treated using the iron chelator deferiprone (DFP) from birth to 2 months of age. Short-wavelength fundus autofluorescence (SW-AF) and spectral-domain optical coherence tomography (SD-OCT) scans were acquired. The bisretinoid levels were quantified using ultra performance liquid chromatography (UPLC) and in vivo through quantitative fundus autofluorescence (qAF). In histologic sections, the photoreceptor cell viability was assessed by measuring the thickness of the outer nuclear layer (ONL).ResultsThe levels of bisretinoids, all-trans-retinal dimers, and A2PE were significantly increased in the FAC-injected eyes of C57BL/6J mice. Seven days after FAC injection, hyperautofluorescent foci were visible in fundus autofluorescence (488 nm) images, and in SD-OCT scans, aberrant hyperreflectivity was present in the outer retina and ONL thinning was observed. In FAC-injected Abca4–/– mice with pronounced RPE bisretinoid lipofuscin accumulation, the hyperautofluorescent puncta were more abundant than in the wild-type mice, and the extent of ONL thinning was greater. Conversely, the intravitreal injection of FAC in Mertk–/– mice led to a more modest increase in A2PE after 2 days. In contrast to the effect of iron accumulation, chelation with DFP resulted in significantly increased levels of A2E and A2-GPE and qAF due to the reduced iron-catalyzed oxidation of bisretinoids. In Mertk–/– mice, the A2E level was significantly lower and the ONL area was smaller than in DFP-treated mice. DFP chelation did not impair the visual cycle in BALB/cJ mice.ConclusionIron accumulation was associated with progressive impairment in photoreceptor cells that was associated with the increased formation of a bisretinoid species known to form in photoreceptor outer segments as a precursor to A2E. Additionally, disease features such as the development of hyperautofluorescence puncta in fundus AF images, hyperreflectivity in the outer retina of SD-OCT scans, and ONL thinning were more pronounced when iron was delivered to Abca4–/– mice with a greater propensity for bisretinoid formation. Higher bisretinoid levels and enhanced qAF are indicative of lesser bisretinoid loss due to oxidation

Retinal basal laminar deposits in complement fH/fP mouse model of dense deposit disease

Purpose: Dense deposit disease (DDD) is caused by dysregulation of the alternative pathway of the complement cascade and characterized by electron-dense deposits in the kidney glomerular basement membrane (GBM) and drusen in Bruch's membrane (BrM). Complement factor H (fH) and factor properdin (fP) regulate complement activation; fH inhibits alternative pathway (AP) activation, whereas fP promotes it. We report pathologic changes in eyes of an fH and fP double-mutant mouse, which we previously showed have dense deposits in the GBM and early mortality from nephropathy.Methods: fHm/m, fP−/−, and fHm/m/fP−/− mice were generated on a C57BL/6–129J background. Fundus imaging at 8 weeks of age was followed by analysis via light and electron microscopy. Retinal function was assessed by electroretinography (ERG). Complement levels and localization were tested by immunohistochemistry and ELISA. Retinas of fHm/m/fP−/− mice treated with intraperitoneal injections of an anti-C5 antibody were compared to those of age- and genotype-matched mice injected with an isotype control antibody.Results: fHm/m/fP−/− mice suffered early-onset retinal hypopigmented spots detected using in vivo retinal photography, and histologic examination showed basal laminar deposits (BLamD), degeneration of the photoreceptors, and RPE vacuolization. ERG showed diminished retinal function. The anti-C5 antibody was retina-protective.Conclusions: This unique mouse represents a new model of complement-mediated rapid-onset DDD, and could be useful in exploring the pathologic changes associated with BLamD in age-related macular degeneration