IU Indianapolis ScholarWorks :: Browsing by Subject "Skin"

Browsing by Subject "Skin"

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Adult skin fibroblast state change in murine wound healing
(Springer Nature, 2023-01-17) Gharbia, Fatma Z.; Abouhashem, Ahmed S.; Moqidem, Yomna A.; Elbaz, Ahmed A.; Abdellatif, Ahmed; Singh, Kanhaiya; Sen, Chandan K.; Azzazy, Hassan M. E.; Surgery, School of Medicine
Wound healing is a well-organized dynamic process involving coordinated consecutive phases: homeostasis, inflammation, proliferation and resolution. Fibroblasts play major roles in skin wound healing such as in wound contraction and release of growth factors which are of importance in angiogenesis and tissue remodeling. Abnormal fibroblast phenotypes have been identified in patients with chronic wounds. In this work, we analyzed scRNA-seq datasets of normal and wounded skin from mice at day 4 post-wound to investigate fibroblast heterogeneity during the proliferative phase of wound healing. Compositional analysis revealed a specific subset of fibroblast (cluster 3) that primarily increased in wounded skin (14%) compared to normal skin (3.9%). This subset was characterized by a gene signature marked by the plasma membrane proteins Sfrp2 + Sfrp4 + Sfrp1 + and the transcription factors Ebf1 + Prrx1 + Maged1 + . Differential gene expression and enrichment analysis identified epithelial to mesenchymal transition (EMT) and angiogenesis to be upregulated in the emerging subset of fibroblasts of the wounded skin. Using two other datasets for murine wounded skin confirmed the increase in cluster 3-like fibroblasts at days 2, 7 and 14 post-wounding with a peak at day 7. By performing a similarity check between the differential gene expression profile between wounded and normal skin for this emerging fibroblast subset with drug signature from the ConnectivityMap database, we identified drugs capable of mimicking the observed gene expression change in fibroblasts during wound healing. TTNPB, verteprofin and nicotinic acid were identified as candidate drugs capable of inducing fibroblast gene expression profile necessary for wound healing. On the other hand, methocarbamol, ifosfamide and penbutolol were recognized to antagonize the identified fibroblast differential expression profile during wound healing which might cause delay in wound healing. Taken together, analysis of murine transcriptomic skin wound healing datasets suggested a subset of fibroblasts capable of inducing EMT and further inferred drugs that might be tested as potential candidates to induce wound closure.
Exploration of bacterial community classes in major human habitats
(Springer Nature, 2014-05-07) Zhou, Yanjiao; Mihindukulasuriya, Kathie A.; Gao, Hongyu; La Rosa, Patricio S.; Wylie, Kristine M.; Martin, John C.; Kota, Karthik; Shannon, William D.; Mitreva, Makedonka; Sodergren, Erica; Weinstock, George M.; Medical and Molecular Genetics, School of Medicine
Background: Determining bacterial abundance variation is the first step in understanding bacterial similarity between individuals. Categorization of bacterial communities into groups or community classes is the subsequent step in describing microbial distribution based on abundance patterns. Here, we present an analysis of the groupings of bacterial communities in stool, nasal, skin, vaginal and oral habitats in a healthy cohort of 236 subjects from the Human Microbiome Project. Results: We identify distinct community group patterns in the anterior nares, four skin sites, and vagina at the genus level. We also confirm three enterotypes previously identified in stools. We identify two clusters with low silhouette values in most oral sites, in which bacterial communities are more homogeneous. Subjects sharing a community class in one habitat do not necessarily share a community class in another, except in the three vaginal sites and the symmetric habitats of the left and right retroauricular creases. Demographic factors, including gender, age, and ethnicity, significantly influence community composition in several habitats. Community classes in the vagina, retroauricular crease and stool are stable over approximately 200 days. Conclusion: The community composition, association of demographic factors with community classes, and demonstration of community stability deepen our understanding of the variability and dynamics of human microbiomes. This also has significant implications for experimental designs that seek microbial correlations with clinical phenotypes.
Global microRNA expression is essential for murine mast cell development in vivo
(Elsevier, 2014-10) Oh, Sun Young; Brandal, Stephanie; Kapur, Reuben; Zhu, Zhou; Takemoto, Clifford; Department of Pediatrics, IU School of Medicine
MicroRNAs (miRNAs) are small, noncoding RNAs that have been shown to play a critical role in normal physiology and disease, such as hematopoietic development and cancer. However, their role in mast-cell function and development is poorly understood. The major objective of this study was to determine how global miRNA expression affects mast-cell physiology. The RNase III endonuclease, Dicer, is required for the processing of pre-miRNAs into mature miRNAs. To investigate the effect of global miRNA depletion on mast cells in vivo, we generated a mast-cell-specific knock out of Dicer in mice. Transgenic mice (Mcpt5-Cre) that express Cre selectively in connective tissue mast cells were crossed with mice carrying the floxed conditional Dicer allele (Dicer fl/fl). Mcpt5-Cre × Dicer fl/fl mice with homozygous Dicer gene deletion in mast cells were found to have a profound mast-cell deficiency with near complete loss of peritoneal, gastrointestinal, and skin mast cells. We examined the in vivo functional consequence of mast-cell-specific Dicer deletion using an immunoglobulin-E-dependent passive systemic anaphylaxis murine model. Immunoglobulin-E-sensitized wild type Mcpt5-Cre × Dicer +/+ and heterozygous Mcpt5-Cre × Dicer fl/+ mice show marked hypothermia with antigen; however, homozygous Mcpt5-Cre × Dicer fl/fl mice were completely unresponsive to antigen challenge. These studies suggest a critical role for Dicer and miRNA expression for establishment of tissue compartments of functional mast cells in vivo
Human keratinocytes utilize the integrated stress response to adapt to environmental stress
(2017-06) Collier, Ann E.; Spandau, Dan F.; Wek, Ronald C.; Travers, Jeffrey B.; Turchi, John J.; Turner, Matthew J.
Human skin, consisting of the outer epidermis and inner dermis, serves as a barrier that protects the body from an onslaught of environmental stresses. Keratinocytes in the stratified epidermis undergo sequential differentiation that consists of multiple layers of cells differing in structure and function. Therefore, keratinocytes must not only combat environmental stress, but need to undergo massive changes in gene expression and morphology to form a proper barrier. One mode by which cells cope with stress and differentiation is through phosphorylation of the α subunit of eukaryotic initiation factor 2 (eIF2α-P), which causes global inhibition of protein synthesis coincident with preferential translation of select gene transcripts. Translational repression allows stressed cells to conserve energy and prioritize pro-survival processes to alleviate stress damage. Since eIF2α kinases are each activated by distinct types of stress, this pathway is referred to as the Integrated Stress Response (ISR). We sought to identify the roles of the ISR in the keratinocyte response to the stresses associated with differentiation and ultraviolet B (UVB) irradiation. In this thesis, we show that both general and gene-specific translational control in the ISR are activated following differentiation or UVB irradiation of human keratinocytes. ISR deficiency through genetic modifications or pharmacological interventions caused severe divergence from the appropriate keratinocyte response to differentiation or UVB. Differentiation genes were selectively translated by eIF2α-P, and inhibition of the ISR diminished their induction during differentiation. Furthermore, loss of the eIF2α kinase GCN2 (EIF2AK4) adversely affected the ability of keratinocytes to stratify in three dimensional cultures. Our analysis also revealed a non-canonical ISR response following UVB irradiation, in which downstream factors ATF4 (CREB2) and CHOP (DDIT3/GADD153) were poorly expressed due to repressed transcription, despite preferential translation in response to eIF2α-P. The ISR was cytoprotective during UVB and we found that eIF2α-P was required for a UVB induced G1 arrest, cell fate determination, and DNA repair via a mechanism involving translational control of human CDKN1A (p21 protein) transcript variant 4 mRNA. Collectively, this thesis describes novel roles for the ISR in keratinocyte differentiation and response to UVB, emphasizing the utility of targeting translational control in skin disease therapy.
The Hyperglycemia Stranglehold Stifles Cutaneous Epithelial‒Mesenchymal Plasticity and Functional Wound Closure
(Elsevier, 2021) Sen, Chandan K.; Roy, Sashwati; Surgery, School of Medicine
Iterative cycles of epithelial-mesenchymal transition (EMT) and mesenchymal to epithelial transition (MET) are responsible for epithelial plasticity necessary to achieve functional wound closure. Restoration of barrier function of the repaired skin is a hallmark of functional wound closure. Both EMT and MET are subject to control by glycemic status. New work in this issue supports the notion that hyperglycemia blunts epithelial plasticity.
Innate Immunity to Staphylococcus aureus: Evolving Paradigms in Soft Tissue and Invasive Infections
(American Association of Immunologists, 2018-06-15) Brandt, Stephanie L.; Putnam, Nicole E.; Cassat, James E.; Serezani, C. Henrique; Microbiology and Immunology, School of Medicine
Staphylococcus aureus causes a wide range of diseases that together embody a significant public health burden. Aided by metabolic flexibility and a large virulence repertoire, S. aureus has the remarkable ability to hematogenously disseminate and infect various tissues, including skin, lung, heart, and bone, among others. The hallmark lesions of invasive staphylococcal infections, abscesses, simultaneously denote the powerful innate immune responses to tissue invasion as well as the ability of staphylococci to persist within these lesions. In this article, we review the innate immune responses to S. aureus during infection of skin and bone, which serve as paradigms for soft tissue and bone disease, respectively.
Insulin-like Growth Factor 1 Receptor Signaling Is Required for Optimal ATR-CHK1 Kinase Signaling in Ultraviolet B (UVB)-irradiated Human Keratinocytes
(American Society for Biochemistry and Molecular Biology, 2017-01-27) Kemp, Michael G.; Spandau, Dan F.; Simman, Richard; Travers, Jeffrey B.; Biochemistry and Molecular Biology, School of Medicine
UVB wavelengths of light induce the formation of photoproducts in DNA that are potentially mutagenic if not properly removed by the nucleotide excision repair machinery. As an additional mechanism to minimize the risk of mutagenesis, UVB-irradiated cells also activate a checkpoint signaling cascade mediated by the ATM and Rad3-related (ATR) and checkpoint kinase 1 (CHK1) kinases to transiently suppress DNA synthesis and cell cycle progression. Given that keratinocytes in geriatric skin display reduced activation of the insulin-like growth factor 1 receptor (IGF-1R) and alterations in DNA repair rate, apoptosis, and senescence following UVB exposure, here we used cultured human keratinocytes in vitro and skin explants ex vivo to examine how IGF-1R activation status affects ATR-CHK1 kinase signaling and the inhibition of DNA replication following UVB irradiation. We find that disruption of IGF-1R signaling with small-molecule inhibitors or IGF-1 withdrawal partially abrogates both the phosphorylation and activation of CHK1 by ATR and the accompanying inhibition of chromosomal DNA synthesis in UVB-irradiated keratinocytes. A critical protein factor that mediates both ATR-CHK1 signaling and nucleotide excision repair is replication protein A, and we find that its accumulation on UVB-damaged chromatin is partially attenuated in cells with an inactive IGF-1R. These results indicate that mutagenesis and skin carcinogenesis in IGF-1-deficient geriatric skin may be caused by defects in multiple cellular responses to UVB-induced DNA damage, including through a failure to properly suppress DNA synthesis on UVB-damaged DNA templates.
Interactions of the Skin Pathogen Haemophilus ducreyi With the Human Host
(Frontiers Media, 2021-02-03) Brothwell, Julie A.; Griesenauer, Brad; Chen, Li; Spinola, Stanley M.; Microbiology and Immunology, School of Medicine
The obligate human pathogen Haemophilus ducreyi causes both cutaneous ulcers in children and sexually transmitted genital ulcers (chancroid) in adults. Pathogenesis is dependent on avoiding phagocytosis and exploiting the suppurative granuloma-like niche, which contains a myriad of innate immune cells and memory T cells. Despite this immune infiltrate, long-lived immune protection does not develop against repeated H. ducreyi infections—even with the same strain. Most of what we know about infectious skin diseases comes from naturally occurring infections and/or animal models; however, for H. ducreyi, this information comes from an experimental model of infection in human volunteers that was developed nearly three decades ago. The model mirrors the progression of natural disease and serves as a valuable tool to determine the composition of the immune cell infiltrate early in disease and to identify host and bacterial factors that are required for the establishment of infection and disease progression. Most recently, holistic investigation of the experimentally infected skin microenvironment using multiple “omics” techniques has revealed that non-canonical bacterial virulence factors, such as genes involved in central metabolism, may be relevant to disease progression. Thus, the immune system not only defends the host against H. ducreyi, but also dictates the nutrient availability for the invading bacteria, which must adapt their gene expression to exploit the inflammatory metabolic niche. These findings have broadened our view of the host-pathogen interaction network from considering only classical, effector-based virulence paradigms to include adaptations to the metabolic environment. How both host and bacterial factors interact to determine infection outcome is a current focus in the field. Here, we review what we have learned from experimental H. ducreyi infection about host-pathogen interactions, make comparisons to what is known for other skin pathogens, and discuss how novel technologies will deepen our understanding of this infection.
Laser Capture Microdissection in the Spatial Analysis of Epigenetic Modifications in Skin: A Comprehensive Review
(Hindawi, 2022-02-09) Bhamidipati, Theja; Sinha, Mithun; Sen, Chandan K.; Singh, Kanhaiya; Surgery, School of Medicine
Each cell in the body contains an intricate regulation for the expression of its relevant DNA. While every cell in a multicellular organism contains identical DNA, each tissue-specific cell expresses a different set of active genes. This organizational property exists in a paradigm that is largely controlled by forces external to the DNA sequence via epigenetic regulation. DNA methylation and chromatin modifications represent some of the classical epigenetic modifications that control gene expression. Complex tissues like skin consist of heterogeneous cell types that are spatially distributed and mixed. Furthermore, each individual skin cell has a unique response to physiological and pathological cues. As such, it is difficult to classify skin tissue as homogenous across all cell types and across different environmental exposures. Therefore, it would be prudent to isolate targeted tissue elements prior to any molecular analysis to avoid a possibility of confounding the sample with unwanted cell types. Laser capture microdissection (LCM) is a powerful technique used to isolate a targeted cell group with extreme microscopic precision. LCM presents itself as a solution to tackling the problem of tissue heterogeneity in molecular analysis. This review will cover an overview of LCM technology, the principals surrounding its application, and benefits of its application to the newly defined field of epigenomics, in particular of cutaneous pathology. This presents a comprehensive review about LCM and its use in the spatial analysis of skin epigenetics. Within the realm of skin pathology, this ability to isolate tissues under specific environmental stresses, such as oxidative stress, allows a far more focused investigation.
Leukotriene B4 licenses inflammasome activation to enhance skin host defense
(National Academy of Science, 2020-12-01) Guerta Salina, Ana Carolina; Brandt, Stephanie L.; Klopfenstein, Nathan; Blackman, Amondrea; Ribeiro Bazzano, Júlia Miranda; Sá-Nunes, Anderson; Byers-Glosson, Nicole; Brodskyn, Claudia; Machado Tavares, Natalia; Santos Da Silva, Icaro Bonyek; Medeiros, Alexandra I.; Serezani, C. Henrique; Microbiology and Immunology, School of Medicine
The initial production of inflammatory mediators dictates host defense as well as tissue injury. Inflammasome activation is a constituent of the inflammatory response by recognizing pathogen and host-derived products and eliciting the production of IL-1β and IL-18 in addition to inducing a type of inflammatory cell death termed "pyroptosis." Leukotriene B4 (LTB4) is a lipid mediator produced quickly (seconds to minutes) by phagocytes and induces chemotaxis, increases cytokine/chemokine production, and enhances antimicrobial effector functions. Whether LTB4 directly activates the inflammasome remains to be determined. Our data show that endogenously produced LTB4 is required for the expression of pro-IL-1β and enhances inflammasome assembly in vivo and in vitro. Furthermore, LTB4-mediated Bruton's tyrosine kinase (BTK) activation is required for inflammasome assembly in vivo as well for IL-1β-enhanced skin host defense. Together, these data unveil a new role for LTB4 in enhancing the expression and assembly of inflammasome components and suggest that while blocking LTB4 actions could be a promising therapeutic strategy to prevent inflammasome-mediated diseases, exogenous LTB4 can be used as an adjuvant to boost inflammasome-dependent host defense.

Browsing by Subject "Skin"

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