Browsing by Author "Guith, Tanner"

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    The eIF2 kinase GCN2 directs keratinocyte collective cell migration during wound healing via coordination of reactive oxygen species and amino acids
    (American Society for Biochemistry and Molecular Biology, 2021-11) Miles, Rebecca R.; Amin, Parth H.; Diaz, Miguel Barriera; Misra, Jagannath; Aukerman, Erica; Das, Amitava; Ghosh, Nandini; Guith, Tanner; Knierman, Michael D.; Roy, Sashwati; Spandau, Dan F.; Wek, Ronald C.; Biochemistry and Molecular Biology, School of Medicine
    Healing of cutaneous wounds requires the collective migration of epithelial keratinocytes to seal the wound bed from the environment. However, the signaling events that coordinate this collective migration are unclear. In this report, we address the role of phosphorylation of eukaryotic initiation factor 2 (eIF2) and attendant gene expression during wound healing. Wounding of human keratinocyte monolayers in vitro led to the rapid activation of the eIF2 kinase GCN2. We determined that deletion or pharmacological inhibition of GCN2 significantly delayed collective cell migration and wound closure. Global transcriptomic, biochemical, and cellular analyses indicated that GCN2 is necessary for maintenance of intracellular free amino acids, particularly cysteine, as well as coordination of RAC1-GTP-driven reactive oxygen species (ROS) generation, lamellipodia formation, and focal adhesion dynamics following keratinocyte wounding. In vivo experiments using mice deficient for GCN2 validated the role of the eIF2 kinase during wound healing in intact skin. These results indicate that GCN2 is critical for appropriate induction of collective cell migration and plays a critical role in coordinating the re-epithelialization of cutaneous wounds.
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    Hydrolyzed Collagen Powder Dressing Improves Wound Inflammation, Perfusion, and Breaking Strength of Repaired Tissue
    (Liebert, 2023) Kumar, Manishekhar; Banerjee, Pradipta; Das, Amitava; Singh, Kanhaiya; Guith, Tanner; Kacar, Sedat; Gourishetti, Karthik; Sen, Chandan K.; Roy, Sashwati; Khanna, Savita; Surgery, School of Medicine
    Hydrolyzed collagen-based matrices are widely used as wound care dressings. Information on the mechanism of action of such dressings is scanty. The objective of this study was to test the effect of a specific hydrolyzed collagen powder (HCP), which is extensively used for wound care management in the United States. The effects of HCP on resolution of wound inflammation, perfusion, closure, and breaking strength of the repaired skin were studied in an experimental murine model. In early (day 7) inflammatory phase of wound macrophages, HCP treatment boosted phagocytosis and efferocytosis of wound-site macrophages. In these cells, inducible reactive oxygen species were also higher on day (d) 7. HCP treatment potentiated the expression of anti-inflammatory interleukin (IL)-10 cytokine and proangiogenic vascular endothelial growth factor (VEGF) production. Excisional wounds dressed with HCP showed complete closure on day 21, while the control wounds remained open. HCP treatment also demonstrated improved quality of wound healing as marked by the improved breaking strength of the closed wound tissue/repaired skin. These data represent first evidence on the mechanism of action of clinically used HCP. HCP dressing favorably influenced both wound inflammation and vascularization. Improved breaking strength of HCP-treated repaired skin lays the rationale for future studies testing the hypothesis that HCP-treated closed wounds would show fewer recurrences.
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    Vaccine for Diabetes-Where Do We Stand?
    (MDPI, 2022-08-22) Chellappan, Dinesh Kumar; Bhandare, Richie R.; Shaik, Afzal B.; Prasad, Krishna; Suhaimi, Nurfatihah Azlyna Ahmad; Yap, Wei Sheng; Das, Arpita; Banerjee, Pradipta; Ghosh, Nandini; Guith, Tanner; Das, Amitava; Balakrishnan, Sarannya; Candasamy, Mayuren; Mayuren, Jayashree; Palaniveloo, Kishneth; Gupta, Gaurav; Singh, Sachin Kumar; Dua, Kamal; Surgery, School of Medicine
    Diabetes is an endocrinological disorder with a rapidly increasing number of patients globally. Over the last few years, the alarming status of diabetes has become a pivotal factor pertaining to morbidity and mortality among the youth as well as middle-aged people. Current developments in our understanding related to autoimmune responses leading to diabetes have developed a cause for concern in the prospective usage of immunomodulatory agents to prevent diabetes. The mechanism of action of vaccines varies greatly, such as removing autoreactive T cells and inhibiting the interactions between immune cells. Currently, most developed diabetes vaccines have been tested in animal models, while only a few human trials have been completed with positive outcomes. In this review, we investigate the undergoing clinical trial studies for the development of a prototype diabetes vaccine.