Browsing by Author "Biswas, Nirupam"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    Inducible miR-1224 silences cerebrovascular Serpine1 and restores blood flow to the stroke-affected site of the brain
    (Elsevier, 2023-01-02) Palakurti, Ravichand; Biswas, Nirupam; Roy, Sashwati; Gnyawali, Surya C.; Sinha, Mithun; Singh, Kanhaiya; Ghatak, Subhadip; Sen, Chandan K.; Khann, Savita; Surgery, School of Medicine
    The α-tocotrienol (TCT) form of natural vitamin E is more potent than the better known α-tocopherol against stroke. Angiographic studies of canine stroke have revealed beneficial cerebrovascular effects of TCT. This work seeks to understand the molecular basis of such effect. In mice, TCT supplementation improved perfusion at the stroke-affected site by inducing miR-1224. miRNA profiling of a laser-capture-microdissected stroke-affected brain site identified miR-1224 as the only vascular miR induced. Lentiviral knockdown of miR-1224 significantly blunted the otherwise beneficial effects of TCT on stroke outcomes. Studies on primary brain microvascular endothelial cells revealed direct angiogenic properties of miR-1224. In mice not treated with TCT, advance stereotaxic delivery of an miR-1224 mimic to the stroke site markedly improved stroke outcomes. Mechanistic studies identified Serpine1 as a target of miR-1224. Downregulation of Serpine1 augmented the angiogenic response of the miR-1224 mimic in the brain endothelial cells. The inhibition of Serpine1, by dietary TCT and pharmacologically, increased cerebrovascular blood flow at the stroke-affected site and protected against stroke. This work assigns Serpine1, otherwise known to be of critical significance in stroke, a cerebrovascular function that worsens stroke outcomes. miR-1224-dependent inhibition of Serpine1 can be achieved by dietary TCT as well as by the small-molecule inhibitor TM5441.
  • Thumbnail Image
    Item
    A Modified Collagen Dressing Induces Transition of Inflammatory to Reparative Phenotype of Wound Macrophages
    (Nature Research, 2019-10-04) Das, Amitava; Abas, Motaz; Biswas, Nirupam; Banerjee, Pradipta; Ghosh, Nandini; Rawat, Atul; Khanna, Savita; Roy, Sashwati; Sen, Chandan K.; Surgery, School of Medicine
    Collagen containing wound-care dressings are extensively used. However, the mechanism of action of these dressings remain unclear. Earlier studies utilizing a modified collagen gel (MCG) dressing demonstrated improved vascularization of ischemic wounds and better healing outcomes. Wound macrophages are pivotal in facilitating wound angiogenesis and timely healing. The current study was designed to investigate the effect of MCG on wound macrophage phenotype and function. MCG augmented recruitment of macrophage at the wound-site, attenuated pro-inflammatory and promoted anti-inflammatory macrophage polarization. Additionally, MCG increased anti-inflammatory IL-10, IL-4 and pro-angiogenic VEGF production, indicating a direct role of MCG in resolving wound inflammation and improving angiogenesis. At the wound-site, impairment in clearance of apoptotic cell bioburden enables chronic inflammation. Engulfment of apoptotic cells by macrophages (efferocytosis) resolves inflammation via a miR-21-PDCD4-IL-10 pathway. MCG-treated wound macrophages exhibited a significantly bolstered efferocytosis index. Such favorable outcome significantly induced miR-21 expression. MCG-mediated IL-10 production was dampened under conditions of miR-21 knockdown pointing towards miR-21 as a causative factor. Pharmacological inhibition of JNK attenuated IL-10 production by MCG, implicating miR-21-JNK pathway in MCG-mediated IL-10 production by macrophages. This work provides direct evidence demonstrating that a collagen-based wound-care dressing may influence wound macrophage function and therefore modify wound inflammation outcomes.
  • Thumbnail Image
    Item
    Myo-Inositol in Fermented Sugar Matrix Improves Human Macrophage Function
    (Wiley, 2022) Ghosh, Nandini; Das, Amitava; Biswas, Nirupam; Mahajan, Sanskruti P.; Madeshiya, Amit K.; Khanna, Savita; Sen, Chandan K.; Roy, Sashwati; Surgery, School of Medicine
    Scope Reactive oxygen species production by innate immune cells plays a central role in host defense against invading pathogens at wound-site. A weakened hos-defense results in persistent infection leading to wound chronicity. Fermented Papaya Preparation (FPP), a complex sugar matrix, bolstered respiratory burst activity and improved wound healing outcomes in chronic wound patients. The objective of the current study was to identify underlying molecular factor/s responsible for augmenting macrophage host defense mechanisms following FPP supplementation. Methods and results In depth LC-MS/MS analysis of cells supplemented with FPP led to identification of myo-inositol as a key determinant of FPP activity towards improving macrophage function. Myo-inositol, in quantities that is present in FPP, significantly improved macrophage respiratory burst and phagocytosis via de novo synthesis pathway of ISYNA1. Additionally, myo-inositol transporters, HMIT and SMIT1, played a significant role in such activity. Blocking these pathways using siRNA attenuated FPP-induced improved macrophage host defense activities. FPP supplementation emerges as a novel approach to increase intracellular myo-inositol levels. Such supplementation also modified wound microenvironment in chronic wound patients to augment myo-inositol levels in wound fluid. Conclusion These observations indicate that myo-inositol in FPP influences multiple aspects of macrophage function critical for host defense against invading pathogens.
  • Thumbnail Image
    Item
    Oncostatin M Improves Cutaneous Wound Re-Epithelialization and Is Deficient under Diabetic Conditions
    (Elsevier, 2022) Das, Amitava; Madeshiya, Amit K.; Biswas, Nirupam; Ghosh, Nandini; Gorain, Mahadeo; Rawat, Atul; Mahajan, Sanskruti P.; Khanna, Savita; Sen, Chandan K.; Roy, Sashwati; Surgery, School of Medicine
    Impaired re-epithelialization characterized by hyperkeratotic non-migratory wound epithelium is a hallmark of non-healing diabetic wounds. In chronic wounds, copious release of oncostatin M (OSM) from wound macrophages is evident. OSM is a potent keratinocyte activator. This work sought to understand the signal transduction pathway responsible for wound-re-epithelialization, the primary mechanism underlying wound closure. Daily topical treatment of full-thickness excisional wounds of C57bl/6 mice with recombinant murine OSM improved wound re-epithelialization and accelerated wound closure by bolstering keratinocyte proliferation and migration. OSM activated the JAK-STAT pathway as manifested by STAT3 phosphorylation. Such signal transduction in the human keratinocyte induced TP63, the master regulator of keratinocyte function. Elevated TP63 induced integrin beta 1, a known effector of keratinocyte migration. In diabetic wounds, OSM was more abundant compared to the level in non-diabetic wounds. However, in diabetic wounds OSM activity was compromised by glycation. Aminoguanidine, a deglycation agent, rescued compromised keratinocyte migration caused by glycated OSM. Finally, topical application of recombinant OSM improved keratinocyte migration and accelerated wound closure in db/db mice. This work recognizes that despite its abundance at the wound-site, OSM is inactivated by glycation and topical delivery of exogenous OSM is likely to be productive in accelerating diabetic wound closure.
  • Thumbnail Image
    Item
    Urolithin A augments angiogenic pathways in skeletal muscle by bolstering NAD+ and SIRT1
    (NPG, 2020-11-11) Ghosh, Nandini; Das, Amitava; Biswas, Nirupam; Gnyawali, Surya; Singh, Kanhaiya; Gorain, Mahadeo; Polcyn, Carly; Khanna, Savita; Roy, Sashwati; Sen, Chandan K.; Surgery, School of Medicine
    Urolithin A (UA) is a natural compound that is known to improve muscle function. In this work we sought to evaluate the effect of UA on muscle angiogenesis and identify the underlying molecular mechanisms. C57BL/6 mice were administered with UA (10 mg/body weight) for 12–16 weeks. ATP levels and NAD+ levels were measured using in vivo 31P NMR and HPLC, respectively. UA significantly increased ATP and NAD+ levels in mice skeletal muscle. Unbiased transcriptomics analysis followed by Ingenuity Pathway Analysis (IPA) revealed upregulation of angiogenic pathways upon UA supplementation in murine muscle. The expression of the differentially regulated genes were validated using quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC). Angiogenic markers such as VEGFA and CDH5 which were blunted in skeletal muscles of 28 week old mice were found to be upregulated upon UA supplementation. Such augmentation of skeletal muscle vascularization was found to be bolstered via Silent information regulator 1 (SIRT1) and peroxisome proliferator-activated receptor-gamma coactivator-1-alpha (PGC-1α) pathway. Inhibition of SIRT1 by selisistat EX527 blunted UA-induced angiogenic markers in C2C12 cells. Thus this work provides maiden evidence demonstrating that UA supplementation bolsters skeletal muscle ATP and NAD+ levels causing upregulated angiogenic pathways via a SIRT1-PGC-1α pathway.