bims-mideyd 2022-01-30 papers

Issue of 2022‒01‒30
three papers selected by
Rajalekshmy “Raji” Shyam, Indiana University Bloomington

Invest Ophthalmol Vis Sci. 2022 Jan 03. 63(1): 30

Hyperglycemia Induces Meibomian Gland Dysfunction.

Yuli Guo, Houjian Zhang, Zhongyang Zhao, Xin Luo, Minjie Zhang, Jinghua Bu, Minghui Liang, Han Wu, Jingwen Yu, Hui He, Rongrong Zong, Yongxiong Chen, Zuguo Liu, Wei Li.

Purpose: Patients diagnosed with diabetes are inclined to have abnormalities on stability of tear film and disorder of meibomian gland (MG). This study aims to explore the pathological change of MG induced by diabetes in a rat model.Methods: Sprague-Dawley (SD) rats were intraperitoneally injected with streptozotocin (STZ) to establish a diabetic animal model. Lipid accumulation in MG was detected by Oil Red O staining and LipidTox staining. Cell proliferation status was determined by Ki67 and P63 immunostaining, whereas cell apoptosis was confirmed by TUNEL assay. Gene expression of inflammatory cytokines and adhesion molecules IL-1α, IL-1β, ELAM1, ICAM1, and VCAM1 were detected by RT-PCR. Activation of ERK, NF-κB, and AMPK signaling pathways was determined by Western Blot analysis. Oxidative stress-related factors NOX4, 4HNE, Nrf2, HO-1, and SOD2 were detected by immunostaining or Western Blot analysis. Tom20 and Tim23 immunostaining and transmission electron microscopy were performed to evaluate the mitochondria functional and structure change.
Results: Four months after STZ injection, there was acini dropout in MG of diabetic rats. Evident infiltration of inflammatory cells, increased expression of inflammatory factors, and adhesion molecules, as well as activated ERK and NF-κB signaling pathways were identified. Oxidative stress of MG was evident in 4-month diabetic rats. Phospho-AMPK was downregulated in MG of 2-month diabetic rats and more prominent in 4-month rats. After metformin treatment, phospho-AMPK was upregulated and the morphology of MG was well maintained. Moreover, inflammation and oxidative stress of MG were alleviated after metformin intervention.
Conclusions: Long-term diabetes may lead to Meibomian gland dysfunction (MGD). AMPK may be a therapeutic target of MGD induced by diabetes.

DOI: https://doi.org/10.1167/iovs.63.1.30

Hum Mol Genet. 2022 Jan 24. pii: ddac013. [Epub ahead of print]

Multi-omics analyses reveal early metabolic imbalance and mitochondrial stress in neonatal photoreceptors leading to cell death in Pde6brd1/rd1 mouse model of retinal degeneration.

Ke Jiang, Anupam Kumar Mondal, Yogita K Adlakha, Jessica Gumerson, Angel Aponte, Linn Gieser, Jung-Woong Kim, Alexis Boleda, Matthew J Brooks, Jacob Nellissery, Donald A Fox, Robert Balaban, Raul Covian, Anand Swaroop.

Retinal diseases exhibit extensive genetic heterogeneity and complex etiology with varying onset and severity. Mutations in over 200 genes can lead to photoreceptor dysfunction and/or cell death in retinal neurodegeneration. To deduce molecular pathways that initiate and/or drive cell death, we adopted a temporal multi-omics approach and examined molecular and cellular events in newborn and developing photoreceptors before the onset of degeneration in a widely-used Pde6brd1/rd1 (rd1) mouse, a model of autosomal recessive retinitis pigmentosa caused by PDE6B mutations. Transcriptome profiling of neonatal and developing rods from the rd1 retina revealed early downregulation of genes associated with anabolic pathways and energy metabolism. Quantitative proteomics of rd1 retina showed early changes in calcium signaling and oxidative phosphorylation, with specific partial bypass of complex I electron transfer, which precede the onset of cell death. Concurrently, we detected alterations in central carbon metabolism, including dysregulation of components associated with glycolysis, pentose phosphate and purine biosynthesis. Ex vivo assays of oxygen consumption and transmission electron microscopy validated early and progressive mitochondrial stress and abnormalities in mitochondrial structure and function of rd1 rods. These data uncover mitochondrial over-activation and related metabolic alterations as determinants of early pathology and implicate aberrant calcium signaling as an initiator of higher mitochondrial stress. Our studies thus provide a mechanistic framework with mitochondrial damage and metabolic disruptions as early drivers of photoreceptor cell death in retinal degeneration.

DOI: https://doi.org/10.1093/hmg/ddac013

Stem Cell Res Ther. 2022 Jan 24. 13(1): 30

Cell maturation influences the ability of hESC-RPE to tolerate cellular stress.

Taina Viheriälä, Heidi Hongisto, Juhana Sorvari, Heli Skottman, Soile Nymark, Tanja Ilmarinen.

BACKGROUND: Transplantation of human pluripotent stem cell-derived retinal pigment epithelium (RPE) is an urgently needed treatment for the cure of degenerative diseases of the retina. The transplanted cells must tolerate cellular stress caused by various sources such as retinal inflammation and regain their functions rapidly after the transplantation. We have previously shown the maturation level of the cultured human embryonic stem cell-derived RPE (hESC-RPE) cells to influence for example their calcium (Ca2+) signaling properties. Yet, no comparison of the ability of hESC-RPE at different maturity levels to tolerate cellular stress has been reported.METHODS: Here, we analyzed the ability of the hESC-RPE populations with early (3 weeks) and late (12 weeks) maturation status to tolerate cellular stress caused by chemical cell stressors protease inhibitor (MG132) or hydrogen peroxide (H2O2). After the treatments, the functionality of the RPE cells was studied by transepithelial resistance, immunostainings of key RPE proteins, phagocytosis, mitochondrial membrane potential, Ca2+ signaling, and cytokine secretion.
RESULTS: The hESC-RPE population with late maturation status consistently showed improved tolerance to cellular stress in comparison to the population with early maturity. After the treatments, the early maturation status of hESC-RPE monolayer showed impaired barrier properties. The hESC-RPE with early maturity status also exhibited reduced phagocytic and Ca2+ signaling properties, especially after MG132 treatment.
CONCLUSIONS: Our results suggest that due to better tolerance to cellular stress, the late maturation status of hESC-RPE population is superior compared to monolayers with early maturation status in the transplantation therapy settings.

Keywords: Cell therapy; Human pluripotent stem cells; Oxidative stress; Retinal pigment epithelial cells

DOI: https://doi.org/10.1186/s13287-022-02712-7