Beneficial mechanisms of dimethyl fumarate in autoimmune uveitis: insights from single-cell RNA sequencing.

BACKGROUND: Dimethyl fumarate (DMF) is a fumaric acid ester that exhibits immunoregulatory and anti-inflammatory properties. However, the function of DMF in autoimmune uveitis (AU) is incompletely understood, and studies comprehensively exploring the impact of DMF on immune cells are still lacking. METHODS: To explore the function of DMF in uveitis and its underlying mechanisms, we conducted single-cell RNA sequencing (scRNA-seq) on the cervical draining lymph node (CDLN) cells of normal, experimental autoimmune uveitis (EAU), and DMF-treated EAU mice. Additionally, we integrated scRNA-seq data of the retina and CDLNs to identify the potential impact of DMF on ocular immune cell infiltration. Flow cytometry was conducted to verify the potential target molecules of DMF. RESULTS: Our study showed that DMF treatment effectively ameliorated EAU symptoms. The proportional and transcriptional alterations in each immune cell type during EAU were reversed by DMF treatment. Bioinformatics analysis in our study indicated that the enhanced expression of Pim1 and Cxcr4 in EAU was reversed by DMF treatment. Further experiments demonstrated that DMF restored the balance between effector T (Teff) /regulatory T (Treg) cells through inhibiting the pathway of PIM1-protein kinase B (AKT)-Forkhead box O1 (FOXO1). By incorporating the scRNA-seq data of the retina from EAU mice into analysis, our study identified that T cells highly expressing Pim1 and Cxcr4 were enriched in the retina. DMF repressed the ocular infiltration of Teff cells, and this effect might depend on its inhibition of PIM1 and CXCR4 expression. Additionally, our study indicated that DMF might reduce the proportion of plasma cells by inhibiting PIM1 expression in B cells. CONCLUSIONS: DMF effectively attenuated EAU symptoms. During EAU, DMF reversed the Teff/Treg cell imbalance and suppressed the ocular infiltration of Teff cells by inhibiting PIM1 and CXCR4 expression. Thus, DMF may act as a new drug option for the treatment of AU.

Single-cell sequencing of the retina shows that LDHA regulates pathogenesis of autoimmune uveitis.

Autoimmune uveitis (AU) is a severe disorder causing poor vision and blindness. However, the cellular dynamics and pathogenic mechanisms underlying retinal injury in uveitis remain unclear. In this study, single-cell RNA sequencing of the retina and cervical draining lymph nodes in experimental autoimmune uveitis mice was conducted to identify the cellular spatiotemporal dynamics and upregulation of the glycolysis-related gene LDHA. Suppression of LDHA can rescue the imbalance of T effector (Teff) cells/T regulator (Treg) cells under inflammation via downregulation of the glycolysis-PI3K signaling circuit and inhibition of the migration of CXCR4+ Teff cells towards retinal tissue. Furthermore, LDHA and CXCR4 are upregulated in the peripheral blood mononuclear cells of Vogt-Koyanagi-Harada patients. The LDHA inhibitor suppresses CD4+ T cell proliferation in humans. Therefore, our data indicate that the autoimmune environment of uveitis regulates Teff cell accumulation in the retina via glycolysis-associated LDHA. Modulation of this target may provide a novel therapeutic strategy for treating AU.

Single-Cell transcriptomes of immune cells provide insights into the therapeutic effects of mycophenolate mofetil on autoimmune uveitis.

Mycophenolate mofetil (MMF) is an immunosuppressive agent widely applied in various autoimmune diseases, including autoimmune uveitis, a sight-threatening autoimmune disease mainly affecting the eyes. However, the mechanisms of action are not comprehensively understood. To investigate the potential impact of MMF on uveitis, we generated single-cell RNA sequence data from normal, experimental autoimmune uveitis (EAU) and MMF-treated EAU mice. We observed that some EAU-induced transcriptional changes were reversed by MMF treatment. Transcriptional data indicated that MMF may have a general inhibitory effect on the activation of immune cells during EAU. Each immune cell type showed a different response to MMF treatment. Pseudotime analysis showed that MMF treatment partly reversed the increased differentiation tendency from naïve to effector phenotypes of T and B cells in EAU. The reduced proportion of T-helper (Th)1 and T-helper (Th)17 cells after MMF treatment was confirmed using flow cytometry. MMF treatment downregulated the EAU-associated upregulation of several molecules (such as Cebpd, Pim1, Furin, Bhlhe40, and Hif1a) that promote pathogenic cytokine production by T helper (Th)-1 and Th17 cells. Abnormally enhanced immunoglobulin production, antigen processing, and presentation ability of B cells may also be inhibited by MMF treatment. In addition to T and B cells, MMF treatment countered EAU-induced transcriptional changes in other immune cells to different degrees. Overall, our findings provide novel insights into the mechanisms underlying MMF treatment and indicate that the therapeutic effect of MMF is not driven by a single molecule.

Identification of Hif1α as a Potential Participant in Autoimmune Uveitis Pathogenesis Using Single-Cell Transcriptome Analysis.

Purpose: This study purposed to depict the transcriptional changes associated with autoimmune uveitis (AU) pathogenesis and identify potential therapeutic targets of this disease. Methods: An experimental AU (EAU) model was established with retina antigen and adjuvants. An EAU control group was established with adjuvant only to eliminate nonspecific effects. We conducted single-cell RNA sequencing (scRNA-seq) on cervical draining lymph node cells of EAU, EAU control, and normal mice to identify the EAU-associated transcriptional changes and the potential pathogenic molecules. Subsequent flow cytometry, adoptive transfer experiment, scRNA-seq analysis of human uveitis, and proliferation assessment were conducted to verify the function of the interested molecule in uveitis. Results: The scRNA-seq data suggested that hypoxia-inducible factor 1 alpha (Hif1α) may participate in EAU pathogenesis via regulating T helper (Th)-17, Th1, and regulatory T cells. Hif1α inhibition alleviated EAU symptoms and regulated Th17, Th1, and regulatory T cell proportions. CD4+ T cells with repressed Hif1α expression failed to transfer EAU to naïve mice. In Vogt-Koyanagi-Harada disease, which is a human uveitis, Hif1α was also increased in CD4+ T cells and regulated their proliferation. Conclusions: The results indicate that Hif1α may participate in AU pathogenesis and are, thus, a potential therapeutic target.

Research progress on pharmacological effects and mechanisms of cepharanthine and its derivatives.

Cepharanthine (CEP) is a bisbenzylisoquinoline alkaloid compound found in plants of the Stephania genus, which has biological functions such as regulating autophagy, inhibiting inflammation, oxidative stress, and apoptosis. It is often used for the treatment of inflammatory diseases, viral infections, cancer, and immune disorders and has great clinical translational value. However, there is no detailed research on its specific mechanism and dosage and administration methods, especially clinical research is limited. In recent years, CEP has shown significant effects in the prevention and treatment of COVID-19, suggesting its potential medicinal value waiting to be discovered. In this article, we comprehensively introduce the molecular structure of CEP and its derivatives, describe in detail the pharmacological mechanisms of CEP in various diseases, and discuss how to chemically modify and design CEP to improve its bioavailability. In summary, this work will provide a reference for further research and clinical application of CEP.

Fabrication of a novel and simple microcystin-LR photoelectrochemical sensor with high sensitivity and selectivity.

Microcystin-LR (MC-LR), an inert electrochemical species, is difficult to be detected by a simple and direct electrochemical method. In the present work, a novel photoelectrochemical sensor is developed on highly ordered and vertically aligned TiO(2) nanotubes (TiO(2) NTs) with convenient surface modification of molecularly imprinted polymer (MIP) (denoted as MIP@TiO(2) NTs) for highly sensitive and selective determination of MC-LR in solutions. Molecularly imprinted polypyrrole (PPy) of MC-LR is chosen as the recognition element. The designed MIP@TiO(2) NTs photoelectrochemical sensor presents excellent applicability in MC-LR determination, with linear range from 0.5 to 100 µg L(-1) and limit of detection of 0.1 µg L(-1). Moreover, the sensor exhibits outstanding selectivity while used in coexisting systems containing 2,4-dichorophenoxyacetic acid, atrazine, paraquat, or monosultap with high concentration, 100 times that of MC-LR. The sensor presents good photoelectric conversion efficiency and detection sensitivity, as well as broad linear detection range, mainly because of the high specific surface area and photoelectric activity of TiO(2) NTs and the π bond delocalized electron system of PPy that promotes the separation of electron-holes. The prominent selectivity is from the MIP by forming multiple hydrogen bonds between PPy and MC-LR. Mechanisms for photoelectrochemical analysis and selective recognition are also discussed.

Thermosensitive Poly(DHSe/PEG/PPG Urethane)-Based Hydrogel Extended Remdesivir Application in Ophthalmic Medication.

The spread of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the coronavirus disease 2019 (COVID-19) outbreak beginning in March 2020. Currently, there is a lack of suitable dose formulations that interrupt novel coronavirus transmission via corneal and conjunctival routes. In the present study, we developed and evaluated a thermosensitive gelling system based on a selenium-containing polymer for topical ocular continuous drug release. In detail, di-(1-hydroxylundecyl) selenide (DHSe), poly(ethylene glycol) (PEG), and poly(propylene glycol) (PPG) were polymerized to form poly(DHSe/PEG/PPG urethane). The polymer was used to carry poorly water-soluble remdesivir (RDV) at room temperature to form the final thermosensitive in situ gel, which exhibited a typical sol-gel transition at 35 °C. The formed polymer was further characterized by rheology, thermology, and scanning electron microscopy. In vitro release studies and in vivo retention and penetration tests indicated that the thermogel provided the prolonged release of RDV. The RDV-loaded in situ gel was proven to be non-biotoxic against human corneal epithelial cells, with good ocular tolerance and biocompatibility in rabbit eyes.

Palmitoylethanolamide (PEA) reduces postoperative adhesions after experimental strabismus surgery in rabbits by suppressing canonical and non-canonical TGFß signaling through PPARα.

Postoperative adhesions and scarring are the particular complication after strabismus surgery, for which there is currently no comprehensive treatment available. Preventing inflammation and fibrosis in the extraocular muscle are crucial for treatment of postoperative adhesions. In the present study, we found that administration of palmitoylethanolamide (PEA) attenuated postoperative inflammation and fibroproliferation through activating peroxisome proliferator-activated receptor α (PPARα), thus prevented scar formation. Inhibition of PEA degradation by N-Acylethanolamine acid amidase (NAAA) inhibitor F96 led to the same pharmacological results. PPARα activation suppressed both canonical and non-canonical TGFß signaling. Mechanistically, we found that PPARα directly bound to TGFß-activated kinase 1 (TAK1), thus preventing its hyperphosphorylation and the activation of downstream p38 and JNK1/2 signaling. Taken together, current study suggested that PEA could be a novel therapeutic approach for postoperative adhesions after strabismus surgery.

Inhibition of ceramide de novo synthesis ameliorates meibomian gland dysfunction induced by SCD1 deficiency.

High expression of stearoyl-CoA desaturase-1 (SCD1) in meibomian glands produces monounsaturated fatty acids that allow the biosynthesis of glycerolipids and other wax-esters but only the low production of sphingolipids. Here, we found that SCD1 deficiency in mice induces the spill of free fatty acids into a parallel pathway for ceramide biosynthesis, resulting in severe meibomian gland dysfunction associated with meibum accumulation in duct lumen and orifices and subsequent atrophy and loss of acinar cells. Genetic and pharmacological inhibition of SCD1 in mice resulted in meibomian gland pathological phenotypes, including local lipid microenvironment alterations, reduced normal cellular differentiation, increased keratinization, inflammatory cell infiltration, cell apoptosis, and mitochondrial dysfunction. However, inhibition of serine palmitoyltransferase, the initial enzyme in ceramide biosynthesis, improved meibomian gland metabolism and morphology in SCD1-deficient mice, resulting in normal cell differentiation and reduced inflammation infiltration, cell apoptosis, and keratinization. These results indicate that elevated levels of endogenous ceramides are a sign of MGD and suggest that inhibition of ceramide de novo biosynthesis could be a new clinical approach to treating MGD.