Pioglitazone-Mediated Peroxisome Proliferator-Activated Receptor γ Activation Aggravates Murine Immune-Mediated Hepatitis

[Effects of chronic intermittent hypoxia and reoxygenation on insulin resistance and skeletal muscle miR-27a-3p/PPARγ/IRS1/PI3K/AKT expressions in rats]

OBJECTIVE

To investigate the effects of chronic intermittent hypoxia (CIH) and reoxygenation on insulin resistance (IR) and expressions of miR-27a-3p/PPARγ/IRS1/PI3K/AKT in rat skeletal muscle.

METHODS

GEO database was used for screening the differentially expressed miRNAs in CIH, and their target genes were subjected to GO and KEGG enrichment analysis followed by construction of the miRNA-mRNA-pathway regulatory network using Cytoscape. In the animal experiment, 48 male SD rats were randomly divided into normoxia group and CIH group (8 weeks of CIH followed by 4 weeks of normoxic recovery). Blood and skeletal muscle samples were collected at baseline, 8 weeks, and 12 weeks to evaluate the changes in fasting blood glucose (FBG) and fasting insulin (FINS) levels and muscular pathology. RT-qPCR and Western blotting were used to detect the changes in the expressions of miR-27a-3p, PPARγ, GLUT4, IRS1, p-IRS1, PI3K, p-AKT and AKT in the muscular tissues.

RESULTS

No muscular miRNA datasets for CIH were available in GEO database, from which only a kidney-related dataset (GSE202480) was obtained, based on which a total of 165 differentially expressed miRNAs were identified. GO/KEGG analysis suggested that these miRNAs were involved in muscular regulation and insulin signaling. The miRNA-mRNA-pathway network highlighted miR-27a-3p as a crucial regulator in the PPAR and PI3K/AKT pathway. In the animal experiment, the rats subjected to CIH for 8 weeks showed significantly increased FBG, FINS, HOMA-IR, and PPARγ levels, loose muscle fiber arrangement, decreased cross-sectional area of the muscle fibers, and lowered expressions of miR-27a-3p, p-IRS1/IRS1, PI3K, and p-AKT/AKT in the skeletal muscles.

CONCLUSION

CIH increases IR, causes skeletal muscle pathology, downregulates miR-27a-3p expression, upregulates PPARγ expression, and inhibits IRS1/PI3K/AKT insulin signaling in the skeletal muscles of rats, and these changes can be reversed by reoxygenation. MiR-27a-3p may participate in CIH-induced IR by modulating the PPAR γ/IRS1/PI3K/AKT signaling pathway.

Application of PPAR Ligands and Nanoparticle Technology in Metabolic Steatohepatitis Treatment

Metabolic dysfunction-associated steatotic liver disease/steatohepatitis (MASLD/MASH) is a major disease worldwide whose effective treatment is challenging. Peroxisome proliferator-activated receptors (PPARs) belong to the nuclear receptor superfamily and function as ligand-activated transcription factors. To date, three distinct subtypes of PPARs have been characterized: PPARα, PPARβ/δ, and PPARγ. PPARα and PPARγ are crucial regulators of lipid metabolism that modulate the transcription of genes involved in fatty acid (FA), bile acid, and cholesterol metabolism. Many PPAR agonists, including natural (FAs, eicosanoids, and phospholipids) and synthetic (fibrate, thiazolidinedione, glitazar, and elafibranor) agonists, have been developed. Furthermore, recent advancements in nanoparticles (NPs) have led to the development of new strategies for MASLD/MASH therapy. This review discusses the applications of specific cell-targeted NPs and highlights the potential of PPARα- and PPARγ-targeted NP drug delivery systems for MASLD/MASH treatment.

Age and sex differences on anti-hyperglycemic medication exposure and risk of newly diagnosed multiple sclerosis in propensity score matched type 2 diabetics

Background

The association between exposure to anti-hyperglycemic medications (A-HgM) for Type 2 Diabetes Mellitus (T2D) treatment and Multiple Sclerosis (MS) in T2D patients is unclear.

Methods

This retrospective cohort analysis used the Mariner claims database. Patient records were surveyed for a diagnosis of MS starting 12 months after diagnosis of T2D. Patients were required to be actively enrolled in the Mariner claims records for six months prior and at least three years after the diagnosis of T2D without a history of previous neurodegenerative disease. Survival analysis was used to determine the association between A-HgM exposure and diagnosis of MS. A propensity score approach was used to minimize measured and unmeasured selection bias. The analyses were conducted between January 1st and April 28th, 2021.

Findings

In T2D patients younger than 45, A-HgM exposure was associated with a reduced risk of developing MS (RR: 0.22, 95%CI: 0.17-0.29, p-value <0.001). In contrast, A-HgM exposure in patients older than 45 was associated with an increased risk of MS with women exhibiting greater risk (RR: 1.53, 95%CI: 1.39-1.69, p < 0.001) than men (RR: 1.17, 95%CI: 1.01-1.37, p = 0 · 04). Patients who developed MS had a higher incidence of baseline comorbidities. Mean follow-up was 6.2 years with a standard deviation of 1.8 years.

Interpretation

In this study, A-HgM exposure in patients with T2D was associated with reduced risk of MS in patients younger than 45 whereas in patients older than 45, exposure to A-HgM was associated with an increased risk of newly diagnosed MS, particularly in women.

Secretome analysis of human schwann cells derived from malignant peripheral nerve sheath tumor

Malignant peripheral nerve sheath tumors (MPNSTs) are highly aggressive, nerve-associated tumors and the main cause of death amongst neurofibromatosis type I (NF1) patients. Schwann cells (SCs) are the pathogenic cell type in MPNST, however the secretome of human MPNST -derived SCs is poorly defined. In this study, a comprehensive proteomic analysis of the proteins secreted by the sNF96.2 human SC line, derived from a patient with MPNST, was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total of 17,354 unique peptides corresponding to 1538 individual proteins were identified. Among them, 995 proteins were confirmed as secreted using various bioinformatics tools including SignalP, SecretomeP, Vertebrate Secretome Database (VerSeDa), and Ingenuity Pathway Analysis (IPA). Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment were conducted to assign protein localization and function, and to define enriched pathways. Protein binding was the most enriched molecular function, and the most enriched biological process was cell-cell adhesion. Metabolic pathways showed the highest levels of enrichment. In addition, 13 of the identified proteins were validated in Western blotting. This comprehensive secretome map constitutes a reference library providing a new molecular insight into MPNST.

The roles of PPARγ and its agonists in autoimmune diseases: A comprehensive review

Autoimmune diseases are common diseases of the immune system that are characterized by the loss of self-tolerance and the production of autoantibodies; the breakdown of immune tolerance and the prolonged inflammatory reaction are undisputedly core steps in the initiation and maintenance of autoimmunity. Peroxisome proliferator-activated receptors (PPARs) are ligand-dependent transcription factors that belong to the nuclear hormone receptor family and act as ligand-activated transcription factors. There are three different isotypes of PPARs: PPARα, PPARγ, and PPARβ/δ. PPARγ is an established regulator of glucose homeostasis and lipid metabolism. Recent studies have demonstrated that PPARγ exhibits anti-inflammatory and anti-fibrotic effects in multiple disease models. PPARγ can also modulate the activation and polarization of macrophages, regulate the function of dendritic cells and mediate T cell survival, activation, and differentiation. In this review, we summarize the signaling pathways and biological functions of PPARγ and focus on how PPARγ and its agonists play protective roles in autoimmune diseases, including autoimmune thyroid diseases, multiple sclerosis, rheumatoid arthritis, systemic sclerosis, systemic lupus erythematosus, primary Sjogren syndrome and primary biliary cirrhosis.