Nrf2 mitigates LRRK2- and α-synuclein-induced neurodegeneration by modulating proteostasis.

Mutations in leucine-rich repeat kinase 2 (LRRK2) and α-synuclein lead to Parkinson's disease (PD). Disruption of protein homeostasis is an emerging theme in PD pathogenesis, making mechanisms to reduce the accumulation of misfolded proteins an attractive therapeutic strategy. We determined if activating nuclear factor erythroid 2-related factor (Nrf2), a potential therapeutic target for neurodegeneration, could reduce PD-associated neuron toxicity by modulating the protein homeostasis network. Using a longitudinal imaging platform, we visualized the metabolism and location of mutant LRRK2 and α-synuclein in living neurons at the single-cell level. Nrf2 reduced PD-associated protein toxicity by a cell-autonomous mechanism that was time-dependent. Furthermore, Nrf2 activated distinct mechanisms to handle different misfolded proteins. Nrf2 decreased steady-state levels of α-synuclein in part by increasing α-synuclein degradation. In contrast, Nrf2 sequestered misfolded diffuse LRRK2 into more insoluble and homogeneous inclusion bodies. By identifying the stress response strategies activated by Nrf2, we also highlight endogenous coping responses that might be therapeutically bolstered to treat PD.

Analysis of Patient-Reported Barriers to Diabetic Retinopathy Follow-Up.

BACKGROUND AND OBJECTIVES: Close follow-up of diabetic retinopathy (DR) has been linked to improved visual outcomes. This study elucidates patient-identified barriers to DR follow-up in a diverse urban clinic population. PATIENTS AND METHODS: Patients 18 years of age or older with DR or macular edema were interviewed using a 21-question survey on attitudes and barriers toward care. Univariate and multivariate logistic analysis identified barriers associated with non-compliance to follow-up. RESULTS: Two hundred nine patients participated with mean age of 58.2 years and hemoglobin A1c of 8.5%. The most common barriers cited were long waiting times (46.4%), other medical conditions (35.9%), forgetting (28.2%), and inability to leave work (9.1%). In a multivariate analysis, forgetting (odds ratio [OR]: 4.35) and other medical conditions (OR: 1.91) were barriers independently associated with non-compliance. Having proliferative DR was associated with other medical conditions in univariate (OR: 4.60) and multivariate analysis (OR: 4.35). CONCLUSION: Patients with DR who report other medical conditions or forgetting have a higher risk of non-compliance to follow-up. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:99-105.].

Factors Associated with Non-compliance for Diabetic Retinopathy Follow-up in an Urban Safety-Net Hospital.

PURPOSE: Diabetic retinopathy (DR) is the leading cause of preventable blindness in working-aged adults, and compliance in ophthalmic follow-up appointments is critical to prevent vision loss. However, barriers to follow-up care have not been well studied, especially in socio-economically disadvantaged groups. We investigated the risk factors for non-compliance to DR follow-up appointments in a safety-net county hospital. METHODS: Two hundred and nine patients who were treated for DR at the Zuckerberg San Francisco General Hospital retina clinic between 1 July 2015 and 30 January 2016 were enrolled in the study. Multivariate logistic regression analysis of demographic and medical information was used to determine independent risk factors for non-compliance to DR follow-up appointments. RESULTS: The mean patient age was 58 years. Sixty-three percent (132/209) of patients were male; the mean haemoglobin A1c level was 8.5 (SD 0.14). Forty-six percent (97/209) of patients attended <80% of their DR follow-up appoinments. Independent risk factors for non-compliance after multivariate logistic regression analysis were diabetic foot involvement [OR: 2.40, 95% CI: (1.04-5.55)] and foot/kidney involvement [OR: 3.79 (1.35-10.5)], history of major depressive disorder (MDD) [OR: 2.11 (1.05-4.26), and having Medi-Cal [OR: 5.01 (2.00-12.5)] or SF Health insurance [OR: 6.79 (2.14-21.5)]. CONCLUSIONS AND RELEVANCE: In conclusion, this is the first study to identify diabetic end organ damage and MDD as independent risk factors for non-compliance in DR follow-up appointments. It is important that health care providers identify these patient subsets and increase efforts to more deliberately encourage follow-up in these high-risk patient groups for DR.

Success in Attaining Independent Funding Among National Institutes of Health K Grant Awardees in Ophthalmology: An Extended Follow-up.

Importance: Understanding factors associated with attaining independent research funding by ophthalmology clinician-scientists receiving National Eye Institute career development awards (K08 or K23) in ophthalmology can be important to maintaining the pipeline of clinician-scientists. Objective: To provide continued follow-up of a cohort of ophthalmology clinician-scientists who received National Institutes of Health (NIH) K career development grants. Design, Setting, and Participants: Cohort study from an electronic database review of ophthalmologists who have received either a K08 or K23 career development grant from the NIH. Data were analyzed between December 30, 2015, and December 30, 2017. Main Outcomes and Measures: Receipt of an NIH R01 grant. Results: We previously characterized a group of more than 100 ophthalmologists who received K awards from 1996 to 2010, of whom 29 were awarded R01 grants. In follow-up of this cohort in 2017, 27 additional K awardees of this initial cohort were awarded an R01 from 2011 to 2017, leading to a total of 62 of 128 ophthalmologists receiving an R01. The mean time to receiving an R01 grant after the K award ended was 2.8 years. The data did not identify a definitive association with sex, having a PhD degree, or research tier of university in obtaining an R01 grant in this cohort. Conclusions and Relevance: In comparison with our previous report of the same cohort, there was a 93% increase in the number of K awardees who have received an R01 award, with the mean time to award being nearly 3 years after completing their K grant. This suggests that most K awardees in ophthalmology are successful in obtaining R01 grants, but one should recognize this may be several years after their K grant has ended.

Obese Neuronal PPARγ Knockout Mice Are Leptin Sensitive but Show Impaired Glucose Tolerance and Fertility.

The peroxisome-proliferator activated receptor γ (PPARγ) is expressed in the hypothalamus in areas involved in energy homeostasis and glucose metabolism. In this study, we created a deletion of PPARγ brain-knockout (BKO) in mature neurons in female mice to investigate its involvement in metabolism and reproduction. We observed that there was no difference in age at puberty onset between female BKOs and littermate controls, but the BKOs gave smaller litters when mated and fewer oocytes when ovulated. The female BKO mice had regular cycles but showed an increase in the number of cycles with prolonged estrus. The mice also had increased luteinizing hormone (LH) levels during the LH surge and histological examination showed hemorrhagic corpora lutea. The mice were challenged with a 60% high-fat diet (HFD). Metabolically, the female BKO mice showed normal body weight, glucose and insulin tolerance, and leptin levels but were protected from obesity-induced leptin resistance. The neuronal knockout also prevented the reduction in estrous cycles due to the HFD. Examination of ovarian histology showed a decrease in the number of primary and secondary follicles in both genotypes due to the HFD, but the BKO ovaries showed an increase in the number of hemorrhagic follicles. In summary, our results show that neuronal PPARγ is required for optimal female fertility but is also involved in the adverse effects of diet-induced obesity by creating leptin resistance potentially through induction of the repressor Socs3.

Astrocyte-Specific Deletion of Peroxisome-Proliferator Activated Receptor-γ Impairs Glucose Metabolism and Estrous Cycling in Female Mice.

Mice lacking peroxisome-proliferator activated receptor-γ (PPARγ) in neurons do not become leptin resistant when placed on a high-fat diet (HFD). In male mice, this results in decreased food intake and increased energy expenditure, causing reduced body weight, but this difference in body weight is not observed in female mice. In addition, estrous cycles are disturbed and the ovaries present with hemorrhagic follicles. We observed that PPARγ was more highly expressed in astrocytes than neurons, so we created an inducible, conditional knockout of PPARγ in astrocytes (AKO). The AKO mice had impaired glucose tolerance and hepatic steatosis that did not worsen with HFD. Expression of gluconeogenic genes was elevated in the mouse livers, as was expression of several genes involved in lipogenesis, lipid transport, and storage. The AKO mice also had a reproductive phenotype with fewer estrous cycles, elevated plasma testosterone levels, reduced corpora lutea formation, and alterations in hypothalamic and ovarian gene expression. Thus, the phenotypes of the AKO mice were very different from those seen in the neuronal knockout mice, suggesting distinct roles for PPARγ in these two cell types.

Free fatty acids induce Lhb mRNA but suppress Fshb mRNA in pituitary LßT2 gonadotropes and diet-induced obesity reduces FSH levels in male mice and disrupts the proestrous LH/FSH surge in female mice.

Female obesity is associated with insulin resistance, hyperandrogenemia, and reproductive dysfunction. We hypothesized that elevated free fatty acids (FFAs) might directly modulate pituitary gonadotropin production. FFAs caused a time- and dose-dependent increase in phosphorylation of the MAPKs p38MAPK, c-Jun N-terminal kinase (JNK)-1/2, and ERK1/2 in LßT2 gonadotrope cells. Furthermore, FFAs up-regulated Lhb mRNA expression acutely, an effect that was blocked by JNK inhibition, but suppressed Fshb mRNA expression, an effect that was independent of MAPK signaling. FFAs enhanced the activation of the MAPKs in the presence of GnRH, although the cotreatment did not alter Lhb induction but did eliminate the GnRH induction of Fshb. FFAs also suppressed activin-induced Fshb expression. Knockdown experiments showed that the FFA effect on the inflammatory kinases p38MAPK and JNK and on Lhb, but not Fshb, mRNA expression is mediated via toll-like receptor-2 and toll-like receptor-4 and was mimicked by lipopolysaccharide stimulation. In vivo, male C57BL/6 mice on a high-fat diet showed reduced FSH levels consistent with the suppression of Fshb seen in vitro. Histological analysis of the testes showed an increased number of abnormal seminiferous tubules. Female mice on a high-fat diet lacked the expected proestrus LH and FSH surge and exhibited an increase in the number of days at estrus and a reduced number of days at proestrus, and ovaries had significantly fewer corpora lutea. Taken together, our findings suggest that lipid excess can lead to reproductive defects in both male and female mice.