Publications by authors named "Jay Lipinski"

5 Publications

  • Page 1 of 1

Epigenetic regulation of the PGE2 pathway modulates macrophage phenotype in normal and pathologic wound repair.

JCI Insight 2020 09 3;5(17). Epub 2020 Sep 3.

Section of Vascular Surgery, Department of Surgery.

Macrophages are a primary immune cell involved in inflammation, and their cell plasticity allows for transition from an inflammatory to a reparative phenotype and is critical for normal tissue repair following injury. Evidence suggests that epigenetic alterations play a critical role in establishing macrophage phenotype and function during normal and pathologic wound repair. Here, we find in human and murine wound macrophages that cyclooxygenase 2/prostaglandin E2 (COX-2/PGE2) is elevated in diabetes and regulates downstream macrophage-mediated inflammation and host defense. Using single-cell RNA sequencing of human wound tissue, we identify increased NF-κB-mediated inflammation in diabetic wounds and show increased COX-2/PGE2 in diabetic macrophages. Further, we identify that COX-2/PGE2 production in wound macrophages requires epigenetic regulation of 2 key enzymes in the cytosolic phospholipase A2/COX-2/PGE2 (cPLA2/COX-2/PGE2) pathway. We demonstrate that TGF-β-induced miRNA29b increases COX-2/PGE2 production via inhibition of DNA methyltransferase 3b-mediated hypermethylation of the Cox-2 promoter. Further, we find mixed-lineage leukemia 1 (MLL1) upregulates cPLA2 expression and drives COX-2/PGE2. Inhibition of the COX-2/PGE2 pathway genetically (Cox2fl/fl Lyz2Cre+) or with a macrophage-specific nanotherapy targeting COX-2 in tissue macrophages reverses the inflammatory macrophage phenotype and improves diabetic tissue repair. Our results indicate the epigenetically regulated PGE2 pathway controls wound macrophage function, and cell-targeted manipulation of this pathway is feasible to improve diabetic wound repair.
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http://dx.doi.org/10.1172/jci.insight.138443DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7526451PMC
September 2020

The evolving role of the lung microbiome in pulmonary fibrosis.

Am J Physiol Lung Cell Mol Physiol 2020 10 2;319(4):L675-L682. Epub 2020 Sep 2.

Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan.

Mucosal surfaces are constantly exposed to a microbiome consisting of microorganisms that heavily influence human immunity and health. In the lung these microorganisms consist of bacteria, viruses, and fungi and exist in a relatively low biomass state. Bacterial communities of the lung modulate local inflammation and correlate with changes in pulmonary physiology and clinical outcomes in patients with lung disease. Instrumental to this progress has been the study of these bacterial communities in the pathogenesis of pulmonary fibrosis, a fatal and progressive disease culminating in respiratory failure. Key pathophysiological mechanisms in pulmonary fibrosis include recurrent idiopathic alveolar epithelial injury, unchecked collagen deposition, mucociliary dysfunction due to muc5b overexpression, hypoxia, and altered host defense. These key mechanisms and their related consequences promote severe progressive architectural lung destruction and loss of local homeostasis. As such, pulmonary fibrosis is an appropriate target disease for the study of the lung microbiome. Herein, we discuss recent advances in our understanding of the role of the lung microbiome in the pathogenesis of pulmonary fibrosis. We highlight fundamental clinical observations and mechanistic insights and identify crucial areas for further discovery science. An improved understanding of how the lung microbiome acts to influence outcomes in patients with pulmonary fibrosis will lead to enhanced therapies for this devastating lung disease.
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http://dx.doi.org/10.1152/ajplung.00258.2020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7642898PMC
October 2020

Epigenetic Regulation of TLR4 in Diabetic Macrophages Modulates Immunometabolism and Wound Repair.

J Immunol 2020 05 23;204(9):2503-2513. Epub 2020 Mar 23.

Section of Vascular Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI 48109;

Macrophages are critical for the initiation and resolution of the inflammatory phase of wound healing. In diabetes, macrophages display a prolonged inflammatory phenotype preventing tissue repair. TLRs, particularly TLR4, have been shown to regulate myeloid-mediated inflammation in wounds. We examined macrophages isolated from wounds of patients afflicted with diabetes and healthy controls as well as a murine diabetic model demonstrating dynamic expression of TLR4 results in altered metabolic pathways in diabetic macrophages. Further, using a myeloid-specific mixed-lineage leukemia 1 (MLL1) knockout ( ), we determined that MLL1 drives expression in diabetic macrophages by regulating levels of histone H3 lysine 4 trimethylation on the promoter. Mechanistically, MLL1-mediated epigenetic alterations influence diabetic macrophage responsiveness to TLR4 stimulation and inhibit tissue repair. Pharmacological inhibition of the TLR4 pathway using a small molecule inhibitor (TAK-242) as well as genetic depletion of either ( ) or myeloid-specific resulted in improved diabetic wound healing. These results define an important role for MLL1-mediated epigenetic regulation of TLR4 in pathologic diabetic wound repair and suggest a target for therapeutic manipulation.
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http://dx.doi.org/10.4049/jimmunol.1901263DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7443363PMC
May 2020

TNF-α regulates diabetic macrophage function through the histone acetyltransferase MOF.

JCI Insight 2020 03 12;5(5). Epub 2020 Mar 12.

Department of Surgery.

A critical component of wound healing is the transition from the inflammatory phase to the proliferation phase to initiate healing and remodeling of the wound. Macrophages are critical for the initiation and resolution of the inflammatory phase during wound repair. In diabetes, macrophages display a sustained inflammatory phenotype in late wound healing characterized by elevated production of inflammatory cytokines, such as TNF-α. Previous studies have shown that an altered epigenetic program directs diabetic macrophages toward a proinflammatory phenotype, contributing to a sustained inflammatory phase. Males absent on the first (MOF) is a histone acetyltransferase (HAT) that has been shown be a coactivator of TNF-α signaling and promote NF-κB-mediated gene transcription in prostate cancer cell lines. Based on MOF's role in TNF-α/NF-κB-mediated gene expression, we hypothesized that MOF influences macrophage-mediated inflammation during wound repair. We used myeloid-specific Mof-knockout (Lyz2Cre Moffl/fl) and diet-induced obese (DIO) mice to determine the function of MOF in diabetic wound healing. MOF-deficient mice exhibited reduced inflammatory cytokine gene expression. Furthermore, we found that wound macrophages from DIO mice had elevated MOF levels and higher levels of acetylated histone H4K16, MOF's primary substrate of HAT activity, on the promoters of inflammatory genes. We further identified that MOF expression could be stimulated by TNF-α and that treatment with etanercept, an FDA-approved TNF-α inhibitor, reduced MOF levels and improved wound healing in DIO mice. This report is the first to our knowledge to define an important role for MOF in regulating macrophage-mediated inflammation in wound repair and identifies TNF-α inhibition as a potential therapy for the treatment of chronic inflammation in diabetic wounds.
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http://dx.doi.org/10.1172/jci.insight.132306DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7141388PMC
March 2020

Protein Arginine Methyltransferase 1 Interacts With PGC1α and Modulates Thermogenic Fat Activation.

Endocrinology 2019 12;160(12):2773-2786

Life Sciences Institute, University of Michigan, Ann Arbor, Michigan.

Protein arginine methyltransferases (PRMTs) are enzymes that regulate the evolutionarily conserved process of arginine methylation. It has been reported that PRMTs are involved in many metabolic regulatory pathways. However, until now, their roles in adipocyte function, especially browning and thermogenesis, have not been evaluated. Even though Prmt1 adipocyte-specific-deleted mice (Prmt1fl/flAQcre) appeared normal at basal level, following cold exposure or β-adrenergic stimulation, impaired induction of the thermogenic program was observed in both the interscapular brown adipose tissue and inguinal white adipose tissue of Prmt1fl/flAQcre mice compared with littermate controls. Different splicing variants of Prmt1 have been reported. Among them, PRMT1 variant 1 and PRMT1 variant 2 (PRMT1V2) are well conserved between humans and mice. Both variants contribute to the activation of thermogenic fat, with PRMT1V2 playing a more dominant role. Mechanistic studies using cultured murine and human adipocytes revealed that PRMT1V2 mediates thermogenic fat activation through PGC1α, a transcriptional coactivator that has been shown to play a key role in mitochondrial biogenesis. To our knowledge, our data are the first to demonstrate that PRMT1 plays a regulatory role in thermogenic fat function. These findings suggest that modulating PRMT1 activity may represent new avenues to regulate thermogenic fat and mediate energy homeostasis. This function is conserved in human primary adipocytes, suggesting that further investigation of this pathway may ultimately lead to therapeutic strategies against human obesity and associated metabolic disorders.
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http://dx.doi.org/10.1210/en.2019-00504DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6853686PMC
December 2019