Activation of Chaperone-Mediated Autophagy Inhibits the Aryl Hydrocarbon Receptor Function by Degrading This Receptor in Human Lung Epithelial Carcinoma A549 Cells

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor and a substrate protein of a Cullin 4B E3 ligase complex responsible for diverse cellular processes. In the lung, this receptor is responsible for the bioactivation of benzo[a]pyrene during tumorigenesis. Realizing that the AHR function is affected by its expression level, we are interested in the degradation mechanism of AHR in the lung. Here, we have investigated the mechanism responsible for AHR degradation using human lung epithelial A549 cells. We have observed that the AHR protein levels increase in the presence of chloroquine (CQ), an autophagy inhibitor, in a dose-dependent manner. Treatment with 6-aminonicotinamide (6-AN), a chaperone-mediated autophagy (CMA) activator, decreases AHR protein levels in a concentration-dependent and time-dependent manner. This decrease suppresses the ligand-dependent activation of the AHR target gene transcription, and can be reversed by CQ but not MG132. Knockdown of lysosome-associated membrane protein 2 (LAMP2), but not autophagy-related 5 (ATG5), suppresses the chloroquine-mediated increase in the AHR protein. AHR is resistant to CMA when its CMA motif is mutated. Suppression of the epithelial-to-mesenchymal transition in A549 cells is observed when the AHR gene is knocked out or the AHR protein level is reduced by 6-AN. Collectively, we have provided evidence supporting that AHR is continuously undergoing CMA and activation of CMA suppresses the AHR function in A549 cells.

OP0133 THE PREVALENCE AND RISK FACTORS OF RETINAL TOXICITY ASSOCIATED WITH LONG-TERM HYDROXYCHLOROQUINE USE

Background:

Hydroxychloroquine (HCQ) is commonly used for the treatment of various autoimmune diseases. The medication is generally well-tolerated. However, long-term use after 5 years may increase the risk of retinopathy. One study in 2014 has demonstrated the risk can be as high as 7.5%. Optical Coherence Tomography (OCT) has become a major modality in screening retinopathy.

Objectives:

To evaluate the prevalence of retinal toxicity among patients using hydroxychloroquine and to determine various risk factors associated with hydroxychloroquine-associated retinal toxicity.

Methods:

We performed a retrospective chart review on a cohort of adult patients with long-term use (≥ 5 years cumulative) of HCQ between January 1st, 2011 to December 31st, 2018 from the Kaiser Permanente San Bernardino County and Riverside medical center areas in Southern California, USA. Patients were excluded if they had previously been diagnosed with retinopathy prior to hydroxychloroquine use, were deceased, or had incomplete OCT exam. Our primary endpoint was the prevalence of patients who developed retinal toxicity detected by OCT, and later confirmed by retinal specialist. Potential risk factors (age, duration of therapy, daily consumption per actual body weight, cumulative dose, confounding diseases and medication) for developing retinopathy were also evaluated. Univariable and multivariable logistic regression analyses were used to determine risk factors associated with retinal toxicity.

Results:

Among 676 patients exposed to more than 5 years of HCQ, the overall prevalence of retinal toxicity was 6.8%, and ranged from 2.5% to 22.2% depending on the age, weight-based dosing, duration of use and cumulative dose. Duration of therapy for 10 years or more increased risk of retinopathy by approximately 5 to 19 folds. Similarly, weight-based dose of 7 mg/kg/day or greater was assciated with increased risk of retinopathy by approximately 5 times. Patients with cumulative dose of 2000 grams or more had greater than 15 times higher risk of developing retinopathy. Duration of use for10 years or more (odd ratio 4.32, 95% CI 1.99 – 12.49), age (odd ratio 1.04; 95% CI 1.01 - 1.08), cumulative dose of more than 1500 g (odd ratio 7.4; 95% CI 1.40 – 39.04) and atherosclerosis of the aorta (odd ratio 2.59; 95% CI, 1.24 – 5.41) correlated with higher risk of retinal toxicity.

Conclusion:

The overall prevalence of retinopathy was 6.8%. Regular OCT screening, especially in patients with hydroxychloroquine use for more than 10 years, daily intake > 7 mg/kg, or cumulative dose > 1500 grams is important in detecting hydroxychloroquine-associated retinal toxicity

References:

[1]Hobbs HE. Sorsby A, & Freedman A. Retinopathy Following Chloroquine Therapy. The Lancet. 1959; 2(7101): 478-480.

[2]Levy, G. D., Munz, S. J., Paschal, J., Cohen, H. B., Pince, K. J., & Peterson, T. Incidence of hydroxychloroquine retinopathy in 1,207 patients in a large multicenter outpatient practice. Arthritis & Rheumatism: 1997; 40(8): 1482-1486.

[3]Ding, H. J., Denniston, A. K., Rao, V. K., & Gordon, C. Hydroxychloroquine-related retinal toxicity. Rheumatology. 2016; 55(6): 957-967.

[4]Stelton, C. R., Connors, D. B., Walia, S. S., & Walia, H. S. Hydrochloroquine retinopathy: characteristic presentation with review of screening. Clinical rheumatology. 2013; 32(6): 895-898.

[5]Marmor, M. F., Kellner, U., Lai, T. Y., Melles, R. B., & Mieler, W. F. Recommendations on screening for chloroquine and hydroxychloroquine retinopathy (2016 revision). Ophthalmology. 2016; 123(6): 1386-1394.

[6]Melles, R. B., & Marmor, M. F. The risk of toxic retinopathy in patients on long-term hydroxychloroquine therapy. JAMA ophthalmology. 2014; 132(12): 1453-1460.

Disclosure of Interests:

None declared

Assessing long-term neuroinflammatory responses to encephalopathy using MRI approaches in a rat endotoxemia model

Sepsis-associated encephalopathy (SAE) induces neuroinflammation, which is associated with cognitive impairment (CI). CI is also correlated with aging. We used contrast-enhanced magnetic resonance imaging (MRI), perfusion MRI, and MR spectroscopy to assess long-term alterations in BBB permeability, microvascularity, and metabolism, respectively, in a rat lipopolysaccharide-induced SAE model. Free radical-targeted molecular MRI was used to detect brain radical levels at 24 h and 1 week post-LPS injection. CE-MRI showed increased Gd-DTPA uptake in LPS rat brains at 24 h in cerebral cortex, hippocampus, thalamus, and perirhinal cortex regions. Increased MRI signal intensities were observed in LPS rat brains in cerebral cortex, perirhinal cortex, and hippocampus regions 1 week post-LPS. Long-term BBB dysfunction was detected in the cerebral cortex at 6 weeks post-LPS. Increased relative cerebral blood flow (rCBF) in cortex and thalamus regions at 24 h, decreased cortical and hippocampal rCBF at 6 weeks, decreased cortical rCBF at 3 and 12 weeks, and increased thalamus rCBF at 6 weeks post-LPS, were detected. MRS indicated that LPS-exposed rat brains had decreased: NAA/Cho metabolite ratios at 1, 3, 6, and 12 weeks; Cr/Cho at 1, 3, and 12 weeks; and Myo-Ins/Cho at 1, 3, and 6 weeks post-LPS. Free radical imaging detected increased radical levels in LPS rat brains at 24 h and 1 week post-LPS. LPS-exposed rats were compared to saline-treated controls. We clearly demonstrated BBB dysfunction, impaired vascularity, and decreased brain metabolites, as measures of long-term neuroinflammatory indicators, as well as increased free radicals in a LPS-induced rat SAE model.

Utility of third trimester sonographic measurements for predicting SGA in cases of fetal gastroschisis

OBJECTIVE

To assess the accuracy of different sonographic estimated fetal weight (EFW) cutoffs, and combinations of EFW and biometric measurements for predicting small for gestational age (SGA) in fetal gastroschisis.

STUDY DESIGN

Gastroschisis cases from two centers were included. The sensitivity, specificity, positive and negative predictive values (PPV and NPV) were calculated for different EFW cutoffs, as well as EFW and biometric measurement combinations.

RESULTS

Seventy gastroschisis cases were analyzed. An EFW<10% had 94% sensitivity, 43% specificity, 33% PPV and 96% NPV for SGA at delivery. Using an EFW cutoff of <5% improved the specificity to 63% and PPV to 41%, but decreased the sensitivity to 88%. Combining an abdominal circumference (AC) or femur length (FL) z-score less than -2 with the total EFW improved the specificity and PPV but decreased the sensitivity.

CONCLUSION

A combination of a small AC or FL along with EFW increases the specificity and PPV, but decreases the sensitivity of predicting SGA.

The natural history of hepatitis B in Asian Americans

PURPOSE

This article provides an overview of the natural history of hepatitis B virus (HBV) infection, its complications, treatment and impact on the Asian American population in the United States. A discussion of the impact that hepatitis B vaccination can have on reducing HBV infection and liver disease is also provided.

METHODS

A review of current literature on the history, diagnosis, complications and treatment of HBV infection was conducted as well as a review of current hepatitis B vaccination efforts.

PRINCIPAL FINDINGS

HBV infection is common in the Asian American population, with 1 in 10 Asian Americans affected. Perinatal and childhood transmission account for most of these chronic cases. Molecular genetic advances have allowed for advances in understanding of this disease in chronically infected individuals. Interferon therapy and/or Lamivudine are currently the main therapies.

CONCLUSIONS

Even though considerable success has been shown with drug therapy, and numerous other agents are under investigation, the high morbidity and mortality from cirrhosis of the liver and hepatocellular carcinoma of those chronically infected with HBV, risk prevention and vaccination will have to be the main foci for future eradication. The combined efforts of public health, health practitioners, immunization and cancer control leaders and voluntary and advocacy organizations are necessary to achieve universal hepatitis B vaccination.

Conformationally restricted mimics of vitamin D rotamers

Drug developments in the vitamin D field have continued to focus on structure-function studies of analogs produced by chemically modifying the structure of 1alpha,25-dihydroxyvitamin D(3) (1,25-D3) and its metabolites. Direct structural information gleaned from X-ray crystallographic or NMR studies regarding the ligand-receptor complex and other guest-host systems, which are likely involved in initiating biologic responses, also offers potential insight into drug design. Evidence has accrued suggesting that topologically different conformers of 1,25-D3 may bind to proteins in different ways, including the induction of different conformations of protein. This paper concerns our progress on the chemical synthesis of analogs (e.g. ansa-steroids, suprasterols, vinylallenes and other analogs) conformationally locked or at least rotationally restricted to mimic higher energy conformers of 1,25-D3.

Developmental patterns of mST3GalV mRNA expression in the mouse: in situ hybridization using DIG-labeled RNA probes

mST3GalV synthesizes ganglioside GM3, the precursor for simple and complex a- and b- series gangliosides, and the expression and regulation of mST3GalV (CMP-NeuAc: lactosylceramide alpha2,3-sialyltransferase) activity is central to the production of almost all gangliosides, a class of glycosphingolipids implicated in variety of cellular processes such as transmembrane signaling, synaptic transmission, specialized membrane domain formation and cell-cell interactions. To understand the developmental expression of mST3GalV in mice, we investigated the spatial and temporal expression of mST3GalV mRNA during the mouse embryogenesis [embryonic (E) days; E9, E11, E13, E15] by in situ hybridization with digoxigenin-labeled RNA probes. All tissues from E9 and E11 were positive for mST3GalV mRNA. On E13, mST3GalV mRNA was expressed in various neural and non-neural tissues. In contrast to these, on E15, the telencephalon and liver produced a strong expression of mST3Gal V which was a quite similar to that of E13. In this stage, mST3GalV mRNA was also expressed in some non-neural tissues. These data indicate that mST3GalV is differently expressed at developmental stages of embryo, and this may be importantly related with regulation of organogenesis in mice.

Molecular cloning and expression of human alpha2,8-sialyltransferase (hST8Sia V)

The cDNA encoding human alpha2,8-sialyltransferase (hST8Sia V) which exhibits activity toward gangliosides, GM1b, GD1a, GT1b, and GD3, was isolated by screening of human brain cDNA library with a DNA probe generated from the cDNA sequence of mouse ST8Sia V (mST8Sia V) and by 5'-RACE of mRNA from human brain tissue. Comparative analysis of this cDNA with mST8Sia V showed that each sequence of the predicted coding region contains 84% identity in both nucleotide and amino acid. Northern analysis of this cDNA indicated that, in contrast to mST8Sia V, two different sizes of transcripts corresponding to 11 and 2.5 kb were expressed in both human fetal and adult brain, while the transcript of 2.5 kb was detected only in adult heart and skeletal muscle. The enzyme expressed in COS cells showed a substrate specificity very similar to that of mST8Sia V.

Fatal hyperphosphatemia following Fleet Phospo-Soda in a patient with colonic ileus

A fatal case of hyperphosphatemia secondary to enteral administration of Fleet Phospo-Soda is presented. A 64-yr-old male admitted for theophylline toxicity was treated with activated charcoal and sorbitol, but subsequently developed colonic ileus. Two sequential doses of Phospo-Soda were administered to facilitate clearance of the charcoal; however, this resulted in marked hyperphosphatemia, hypocalcemia, acidemia, and other electrolyte abnormalities, followed by the patient's demise. This case is added to several other reports about the risks of injudicious use of sodium phosphate cathartics.